Britney Spears revved up the celebration for sons Preston and Jayden on Saturday, throwing her sons a joint car and truck-themed birthday bash in Los Angeles.

Spears celebrated her boys' special days - Preston turns 3 on Sept. 14, and Jayden turned 2 on Sept. 12 - with sister Jamie Lynn Spears, her newborn niece Maddie Briann, dad Jamie and mom Lynne.

Held at close friend Adrienne Maloof-Nassif's Beverly Park house, the outdoor party drew some famous guests, including Jenny McCarthy with her son Evan, and Gwen Stefani's son Kingston, 2, who came to the bash from an equally starry affair: He celebrated Heidi Klum's son Henry's 3rd birthday at the model's Beverly Hills house along with all three of Victoria Beckham's sons.