More photos from OK Magazine

Britney stops at McDonalds

Britney leaving 'Womanizer' video shoot

Sean Preston and Jayden James at the Zoo

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Britney at the International Dance Studio

Britney at a dance studio in Hollywood

Britney leaves the International Dance Academy

Britney at a Polo Match in Pacific Palisades

Britney at Calypso on Sunset Plaza

Britney spending time with her kids

Britney at Starbucks in Los Angeles

Britney at the International Dance Academy

Britney spending time with her family

Britney leaving Starbucks Coffee

Britney and Jamie Lynn at a video store

Britney throws a birthday party for sons

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.

And the party was truly a family affair.

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.

But the guests of honor seemed to be having the best time. Preston and Jayden drove around the party in mini motorized cars, which were customized Ed Hardy by Christian Audigier. The cars featured tattoo-inspired decals, Ed Hardy air fresheners and personalized license plates. To keep with the party's theme, the cake was in shape of a yellow truck.

"The boys received tons of birthday gifts," a source told PEOPLE. "Britney and her family really made the party special for the boys."

Happy Birthday Sean Preston !!!

~ Preston turns THREE today ~

Britney at The Little Door restaurant

Sean Preston leaving My Gym

Britney arriving at Magnolia restaurant

Britney donates painting for charity

Britney Spears and her family have donated an autographed portrait of the singer for charity, with a starting bid of $10,000 on eBay.

The 5-by-4-foot oil painting of the pop star was given to the L.A.-based Promises Foundation, which provides behavioral health services to low-income women and their children.

"The Spears family gave us this painting out of their generosity," says the organization's director, Lisa Rogg. "It was their idea for the auction."

The eBay page shows several photos of Spears standing next to the artwork, as well as a letter of authenticity from her father, Jamie, which states: "I hereby verify that the portrait of my daughter, Britney, has been in our home since it was completed by the Daniel Maltman Studio."

Source: People

Happy Birthday Jayden James!

~ Jayden turns TWO today ~