Foraging in Chicagoland

I saw a cursory article in the Chicago Tribune today about collecting edible weeds. I've heard people talk about foraging for ramps and some edible flowers and greens. I'm curious what other items can be foraged. Are there any good guides? Particular areas that are rich with gatherable goods?

Many thanks,

rien

For Chicagoland specific info you might try a camping store.For general info the Euell Gibbons books.