Ibrutinib in Treating Patients With Relapsed or Refractory Follicular Lymphoma

Inclusion Criteria: * Histologically confirmed diagnosis of follicular lymphoma, grade 1, 2, or 3a * Note: Fresh (frozen) tumor biopsy must be available or attempted; a frozen tumor biopsy equivalent to a minimum of four at least 16 gauge needle cores is an important component of this study; patients without adequate frozen material should have a biopsy performed to obtain material; if biopsy is performed and does not yield adequate material, the patient is still eligible for the study; if a biopsy cannot be done safely, the patient may still be eligible for the study if permission is granted in writing (email) by the study chair (Dr. Nancy Bartlett) or her designees; Dr. Bartlett may be consulted to discuss situations involving invasive biopsy procedures that may pose an increased risk to the patient * Measurable disease as defined by a lymph node or tumor mass that is \>= 1.5 cm in at least one dimension by CT or the CT portion of the PET/CT * Relapsed or refractory follicular lymphoma which has progressed during or following 1 or more prior chemotherapy regimens for lymphoma * Eastern Cooperative Oncology Group (ECOG) performance status (PS) 0, 1 or 2 * Absolute neutrophil count \>= 750/mm\^3 (0.75 x 10\^9/L) * Hemoglobin \>= 8.0 g/dL * Platelets \>= 30,000/mm\^3 (30 x 10\^9/L) * Total bilirubin =\< 1.5 x institutional upper limit of normal (ULN) unless Gilbert's syndrome or disease infiltration of the liver is present * Aspartate aminotransferase (AST) (serum glutamic…