Its not foraging, per se, but check Craigslist in season. There are usually people trying to get rid of their mountains of zucchini :) Also, some people are willing to let you come pick from their fruit trees. If the fruit is unused (crabapples, in our area) it drops to the ground and creates a mess for the homeowner.
Also, another shout-out for blackberries. They are weeds out here, and they taste so much better than the ones in the store!