Inclusion Criteria:

          -  Patients must have follicular lymphoma (grade I, II or IIIa) confirmed at initial
             diagnosis and at relapse with identifiable fludeoxyglucose F-18 (FDG) avid disease on
             PET/CT; patients that have involvement with large cell lymphoma are not eligible

          -  Patients must not have clinical evidence of central nervous system involvement by
             lymphoma since the proposed treatment strategies are not designed to address central
             nervous system (CNS) involvement adequately; if performed, any laboratory or
             radiographic tests performed to assess CNS involvement must be negative

          -  Patients must have a whole body or limited whole body PET/CT scan performed within 42
             days prior to registration

          -  Patients must have bone marrow biopsy performed within 42 days prior to registration

          -  All disease must be assessed and documented on the S1608 FDG-PET/CT assessment form

          -  The intent is to enroll patients with FL relapsed within 2 years of completing their
             first course of chemotherapy (CHOP or bendamustine based therapy) + anti-CD20 therapy.
             Patient is still eligible if he/she received radiation therapy or anti-CD20 therapy
             prior to chemoimmunotherapy or if maintenance anti-CD20 therapy was administered after
             chemoimmunotherapy

               -  Patients must have either failed to achieve a complete remission, or must have
                  relapsed within 2 years after completing CHOP or bendamustine-containing
                  chemoimmunotherapy (including an anti-CD20 monoclonal antibody), as measured from
                  the last dose of CHOP or bendamustine; relapsed patients must not have received
                  any intervening chemotherapy

               -  Patients must have received only 1 course of chemotherapy, containing at least 3
                  cycles of CHOP or bendamustine; (note that no minimum dose of bendamustine is
                  required)

               -  Patients who received any anti-CD20 antibody therapy prior to CHOP or
                  bendamustine are eligible

               -  Patients who additionally received any maintenance anti-CD-20 antibody therapy or
                  consolidative radioimmunotherapy within 2 years of the last dose of the CHOP or
                  bendamustine therapy are eligible

               -  Involved field or involved site radiation is not considered a line of therapy;
                  examples of eligible prior treatment regimens (note this list is not all
                  inclusive):

                    -  1st line rituximab treatment followed years later by bendamustine rituximab
                       x 4 cycles

                    -  Bendamustine rituximab x 4 cycles

                    -  1st line rituximab treatment, 2nd line ibritumomab tiuxetan, followed by
                       bendamustine bortezomib rituximab x 6 cycles followed by rituximab
                       maintenance

                    -  Bendamustine obinutuzumab x 3 cycles

                    -  CHOP rituximab x 6 cycles followed by rituximab maintenance

          -  For all forms of systemic therapy, patients must have completed therapy at least 21
             days prior to registration; patients must have completed any radioimmunotherapy at
             least 84 days prior to registration; patients must have recovered from all treatment
             related toxicities from these therapies prior to registration

          -  Patients must not have any prior treatment with any PI3K inhibitor, or lenalidomide

          -  Patients must have tissue specimens collected prior to registration; patients must be
             offered participation in biobanking of residual specimens; with patient consent,
             residuals from the mandatory submission will be banked for future research

          -  All patients must have a Zubrod performance status of 0, 1 or 2

          -  Absolute neutrophil count (ANC) >= 1,500/mcL within 28 days prior to registration

          -  Platelets >= 75,000/mcL within 28 days prior to registration

          -  Patients must have adequate renal function as documented by a calculated creatinine
             clearance >= 60 mL/min, within 28 days prior to registration

          -  Total bilirubin =< 1.5 x institutional upper limit of normal (IULN) (=< 5 x IULN if
             secondary to lymphoma, Gilbert's syndrome, or medication related [e.g., indinavir,
             tenofovir, atazanavir]) within 28 days prior to registration

          -  Direct bilirubin =< 1.5 x IULN (=< 5 x IULN if secondary to lymphoma) within 28 days
             prior to registration

          -  Aspartate aminotransferase (AST) and alanine aminotransferase (ALT) =< 2.5 x IULN (=<
             5 x IULN secondary to lymphoma) within 28 days prior to registration

          -  Patients must have an echocardiogram (ECHO) or multigated acquisition (MUGA) scan
             within 42 days prior to registration with a cardiac ejection fraction >= 45%

          -  Patients with hepatitis B virus infection must have undetectable hepatitis B virus
             (HBV) on suppressive therapy and no evidence of HBV-related hepatic damage; patients
             with hepatitis C virus infection are eligible if complete eradication therapy has been
             successfully completed, and there is no detectable hepatitis C virus (HVC) or related
             hepatic damage; patients with known human immunodeficiency virus (HIV) infection are
             eligible if they meet all of the following criteria in addition to the other protocol
             eligibility criteria:

               -  Patient must have no history of acquired immune deficiency syndrome
                  (AIDS)-related complications, other than a history of low CD4+ T-cell count (<
                  200/mm^3) prior to initiation of combination antiretroviral therapy; on study
                  CD4+ T-cell count may not be informative due to leukemia and should not be used
                  as an exclusion criterion if low

               -  Patient must be healthy on the basis of HIV disease with high likelihood of near
                  normal life span were it not for the leukemia

               -  Patient must have serum HIV viral load of < 200 copies/mm^3

               -  Patient must be on combination antiretroviral therapy with minimal
                  pharmacokinetic interactions with study therapy and minimal overlapping clinical
                  toxicity with protocol therapy; (recommend a regimen of the integrase inhibitor
                  dolutegravir combined with either disoproxil fumarate/emtricitabine or
                  dolutegravir combined with tenofovir alafenamide/emtricitabine)

               -  Protease inhibitors and once daily formulations containing cobicistat are NOT
                  allowed due to potential pharmacokinetic interactions with leukemia therapy

               -  Stavudine and zidovudine (AZT) are NOT allowed because of overlapping toxicity
                  with protocol therapy

          -  Patients must be able and willing to receive prophylaxis with daily aspirin, low
             molecular weight heparin, factor X inhibitors or warfarin if randomized to
             lenalidomide; patients must also be willing to receive pneumocystis jirovecii
             prophylaxis with sulfamethoxazole/trimethoprim, dapsone, atovaquone or inhaled
             pentamidine, in the event that they are randomized to TGR-1202; patients unable or
             unwilling to take any listed prophylaxis are NOT eligible

          -  Patients must be able to discontinue CYP2C9 substrates with a narrow therapeutic index
             (e.g. warfarin, phenytoin), if randomized to TGR-1202; patients must discontinue such
             agents at least 1 week or 5 half-lives prior to beginning protocol therapy (whichever
             is longer)

          -  No second prior malignancy is allowed except for adequately treated basal (or squamous
             cell) skin cancer, in situ cervical cancer or other cancer for which the patient has
             been disease free for three years

          -  Patients must have a complete history and physical examination within 28 days prior to
             registration

          -  Females of childbearing potential (FCBP) must have a negative serum or urine pregnancy
             test with a sensitivity of at least 25 mIU/mL within 10-14 days and again within 24
             hours prior to starting cycle 1 of lenalidomide; further, they must either commit to
             complete abstinence (true abstinence is acceptable when this is in line with the
             preferred and usual lifestyle of the subject; periodic abstinence [e.g., calendar,
             ovulation, symptothermal or post ovulation methods] and withdrawal are not acceptable
             methods of contraception) from heterosexual intercourse or begin TWO acceptable
             methods of birth control: one highly effective method and one additional effective
             method AT THE SAME TIME, at least 28 days before starting lenalidomide; while taking
             lenalidomide, during dose interruptions, and for at least 28 days after the last dose
             of lenalidomide; FCBP must also agree to ongoing pregnancy testing; men must agree to
             use a latex condom during sexual contact with a FCBP, even if they have had a
             successful vasectomy; a FCBP is a female who: 1) has achieve menarche at some point;
             2) has not undergone a hysterectomy or bilateral oophorectomy; or 3) has not been
             naturally postmenopausal (amenorrhea following cancer therapy does not rule out
             childbearing potential) for at least 24 consecutive months (i.e., has had menses at
             any time in the preceding 24 consecutive months); all patients must be counseled by a
             trained counselor every 28 days about pregnancy precautions and risks of fetal
             exposure; NOTE: patients not randomized to receive lenalidomide will not be required
             to undergo serial pregnancy testing or lenalidomide counseling after registration

          -  Patients must have lactate dehydrogenase (LDH) and beta-2-microglobulin collected
             within 28 days prior to registration

          -  Patients must be informed of the investigational nature of this study and must sign
             and give written informed consent in accordance with institutional and federal
             guidelines

          -  As a part of the Oncology Patient Enrollment Network (OPEN) registration process the
             treating institution's identity is provided in order to ensure that the current
             (within 365 days) date of institutional review board approval for this study has been
             entered in the system