So here's what we do. We start a non-profit which buys CSA shares, and uses them to provide low-income kids at after-school programs one nutritious, probably organic meal a day. Free to the after-school programs, great for the kids -- both developmentally and in learning to enjoy the taste of healthy food -- and creates a demand for more CSAs, which is an a priori good thing. (CSA == Community Supported Agriculture, for those of you who aren't foodies/non-profit junkies.)
That's Phase One; Phase Two is getting growing space of our own, both to provide produce, but also to allow the kids to have interaction with the farming process. If they grow green beans, they'll be more likely to eat green beans.
Phase Three is expanding the concept to other cities.