Drew Barrymore, Mandy Moore, President Bill Clinton, and nearly 800 college students congregated at the San Diego Food Bank in Southern California yesterday. Drew and the former president addressed the crowd before rolling up their sleeves and boxing up school lunches. Giving back seems to come easy for Drew, who visited Las Vegas last week to present her close pal Cameron Diaz with an award at CinemaCon. Drew's boyfriend and constant PDA partner, Will Kopelman, joined her on the trip to Sin City, but she was solo for yesterday's outing. Mandy, too, was without her husband, Ryan Adams, but tweeted her excitement about volunteering, meeting the president, and raising awareness for a charitable cause.