Celtics forward Jared Sullinger will be at Goodwill headquarters on Harrison Avenue on Tuesday to sign autographs and take pictures with people who donate seven items or more. (The number isn’t arbitrary; Sullinger is the team’s No. 7.) The gently-used items will support Goodwill’s job training, career services, and youth programs. Sullinger will be there from 5:30 to 7 p.m. There will also be a raffle for tickets to a game.