This weekend, Slow Food Nation is taking over San Francisco's City Hall with food vendors, conferences, workshops, and farming demos. All last month I got to watch as hearty volunteers turned the stinky, pigeon-befouled strip of concrete in front of City Hall into an amazing herb and vegetable garden. It reminded me of the sustainable, organic backyard garden I grew up with in Oregon, long before "green" was hip. There were the same kinds of vegetables—squash, cucumbers, tomatos, corn, beans—as