Given that this is a supermarket blog, you might be surprised that I'd post a video that's not exactly sympathetic to the commercial food system of the US. But this is a really important issue that Ron Finley, a self-proclaimed "guerilla gardener" from South Central LA, addresses head-on in this TED Talk. It's definitely worth the 11 minutes to watch this one.
"Growing your own food is like printing your own money." Except not illegal. Don't try that at home, kids.