Legendary gospel and soul icon Mavis Staples returns to the Payomet Performing Arts Center, 29 Old Dewline Road in Truro, on Sunday, Aug. 1, 7 p.m. On the eve of her 80th birthday, Staples says that “I sing because I want to leave people feeling better than I found them.” Tickets are between $55 and $75 at payomet.org.