Depends on where in the bay area you're talking about. In SF itself, the parks are still giving up silver, if you know how to do it

Same for certain parks in the east bay. Elsewhere in the bay area I've done good at old-town urban demolition sites, when I've been lucky enough to stumble onto them in progress.
There's 4 clubs in the bay area that meet 1x p/month: 1 in San Jose, 1 in Concord, another just south of SF, and another in San Rafael (or near there). There's also a CA specific forum "kinzli" forum. To get past the beginner page you have to sign up (to prevent spam, etc..) but it's easy: just pick a name and password. You'll find bay area folks on there.