Keep an eye out at Mariposa Park — you're bound to uncover some treasure or funny trinket among the stalls here. After you've had a good look at the wares, try some fare from one of the food vendors.
This community marketplace is located in the residential neighborhood of Shoreline West. Mariposa Park is free to visit, making for a fun and cheap day out! Be sure to set aside enough time to explore a few nearby sights, such as Computer History Museum, Stanford Shopping Center and Shoreline Park.