Huddart Park in San Mateo county, CA has a free outdoor archery range open to the public (as well as many other features such a trails, picnic facilities, etc).
EastBayExpress' blurb about the Redwood Bowmen Association's free outdoor archery range in the hills of Oakland, CA. On the trails, it's a bit like golf, in a forest, with bows. Probably the most fun I've had at a range was here.