This randomized phase II trial studies how well obinutuzumab with or without PI3K-delta inhibitor TGR-1202, lenalidomide, or combination chemotherapy work in treating patients with grade I-IIIa follicular lymphoma that has come back or does not respond to treatment. Monoclonal antibodies, such as obinutuzumab, may interfere with the ability of cancer cells to grow and spread. PI3K-delta inhibitor TGR-1202 may stop the growth of cancer cells by blocking some of the enzymes needed for cell growth. Biological therapies, such as lenalidomide, use substances made from living organisms that may stimulate or suppress the immune system in different ways and stop cancer cells from growing. Drugs used in chemotherapy, such as cyclophosphamide, doxorubicin hydrochloride, vincristine sulfate, and prednisone, work in different ways to stop the growth of cancer cells, either by killing the cells, by stopping them from dividing, or by stopping them from spreading. It is not yet known whether giving obinutuzumab with or without PI3K-delta inhibitor TGR-1202, lenalidomide, or combination chemotherapy will work better in treating patients with grade I-IIIa follicular lymphoma. Eligibility includes being at least 18 years old and 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. Contact Mercy clinical trials for further eligibility requirements.