Recovered pop mom Britney Spears is working on her career comeback -- but this weekend, her priorities were sons Sean Preston and Jayden James, who turned 2 and 3, respectively -- treating the tots to a truck-themed party.

Judging from the star-studded guest list, the boys know how to party with Hollywood's elite! Auntie Jamie Lynn stopped by with newborn daughter Maddie Briann, as well as Jenny McCarthy with son Evan, and Gwen Stefani with her boy Kingston.

"The boys received tons of birthday gifts," a party source told People magazine. "Britney and her family really made the party special for the boys." The guests of honor were each gifted a mini motorized truck, customized by Ed Hardy guru Christian Audigier.