Howdy All,
I found this while surfing the 'net this morning. I thought it was a pretty interesting article. I don't live in the city per se, but I'm fairly close to a good sized one. When my wife and I are out for an evening walk, I always keep my eyes open for the edibles. Some are clearly on private property but others are not. I've found a pear tree, mulberry tree, walnuts, and all kinds of edible "weeds".
LW
http://articles.moneycentral.msn.com/CollegeAndFamily/RaiseKids/live-off-the-land-in-the-city.aspx