Gwen Stefani and Gavin Rossdale spent yesterday afternoon at a Malibu park with their sons, Kingston and Zuma, who fueled up on pastries before hitting the swings. The foursome have been all about soaking up the Southern California sun lately, after a recent trip to the beach and a wagon ride adventure. Gavin will soon be back to work, as he's got new shows with Bush lined up following their July concert in Chicago. Gwen, meanwhile, will make a cameo on the small screen during this season of The Rachel Zoe Project, which debuted last night.