This phase I/II trial is studying the best dose of FR901228 when given together with rituximab and fludarabine and to see how well FR901228 works alone in treating patients with relapsed or refractory low-grade B-cell non-Hodgkin's lymphoma. Drugs used in chemotherapy, such as FR901228 and fludarabine, work in different ways to stop cancer cells from dividing so they stop growing or die. Monoclonal antibodies, such as rituximab, can locate cancer cells and either kill them or deliver cancer-killing substances to them without harming normal cells. Rituximab may increase the effectiveness of chemotherapy drugs by making cancer cells more sensitive to the drugs.