A bright orange fiberglass carrot hangs outside the entrance to "L.A. Exuberance," a show that comprises gifts artists gave to LACMA this past year. The museum turned 50 last year, so L.A.-based artist Catherine Opie led a birthday campaign, encouraging her peers to donate their art (she gave her stirring series of photographs from Obama’s 2009 inauguration). John Baldessari made the carrot. He also gave a number of works from his collection, including a painting by Meg Cranston of an eager puppy beneath what is either the sun or a fried egg. The show has a festive mood. Joe Sola’s More Cinematic LACMA on Fire, a video riff on Ed Ruscha’s 1965 painting of the museum in flames, serves as something of a roast: Onlookers gawk as black smoke billows above LACMA’s Ahmanson Building.