05/09/2011 at 04:25 PM EDT
got the party started at Trousdale lounge
in Los Angeles. The singer-actor and his pals took over part of the back room, where they ordered bottles of champagne. "He was in great spirits," a source tells PEOPLE. "He was nice and friendly with everyone he talked to, laughing and making jokes to his guy friends." Though he talked to a few lucky ladies, he was focused on having fun with his friends. Later, Gossip Girl
's Chace Crawford
, there with his own group, stopped by to say hello.
What a good son! Jake Gyllenhaal
spent Mother's Day with mom Naomi Foner at Intelligentsia Coffee and Tea in Venice, Calif. The actor, dressed down in a white T-shirt and blue baseball hat, chatted away with his mom while they waited for their drinks. "They looked adorable and like they were having a great time," an onlooker tells PEOPLE.
Elsewhere on Sunday, Kelly Osbourne
stepped out with David Arquette
and some friends at Yellowtail in Las Vegas. The group enjoyed a leisurely dinner prepared by chef Akira Back, and savored the restaurant's signature tuna pizza. After the meal, they headed to The Bank nightclub at the Bellagio.
Also in Las Vegas over the weekend: Jamie Lynn Spears
, who had dinner with 2½-year-old daughter Maddie and some family friends at Simon at the Palms Place. The starlet enjoyed bigeye tuna, while her little one munched on some macaroni and cheese. Earlier in the day, the mother-daughter duo played in the sunshine at the Palms Place Hotel & Spa pool.
A handful of stars spent Mother's Day doing some good: Halle Berry
, Alyson Hannigan
and Modern Family
's Eric Stonestreet
pumped up participants at the 18th Annual EIF Revlon Run/Walk For Women in Los Angeles. Berry sent the runners on their way, cheering for racers as they crossed the starting line. Hannigan, meanwhile, participated in the race with girlfriends, while Stonestreet drove a pace car as his girlfriend ran.
By JENNIFER GARCIA, MARK GRAY and JESSICA WEDEMEYER