"The mighty American chestnut tree once was an integral part of Eastern forests, but it has been virtually wiped out by a fungus. Luckily for people in the Bay Area who'd like to enjoy chestnuts, though, a few small groves of other varieties survive locally."Link.
U-pick chestnuts on the peninsula
I can't say that I love to eat roasted chestnuts, but walking through a chestnut grove sounds like a nice way to pass a couple of hours on an autumn afternoon.