Gwen Stefani: Kingston and Zuma's Park Playtime

Gwen Stefani and her spends an afternoon at the park with her kids in Beverly Hills, Calif. on Thursday (October 1).

Kingston Rossdale, 3, and Zuma, 1, played as mama Gwen, 39, kept a watchful eye over her boys. Love that she’s rocking harem pants – take that, mom jeans!

The busy singer, L.A.M.B. designer and mom, who’ll be celebrating her 40th birthday tomorrow, told USA Today that she wants “a really big cake” for her big day.

Happy early birthday!

FYI: Kingston is playing with his LikeABike wooden balance bicycle!

30+ pictures inside of Gwen Stefani and her boys playing in the park…