Local:
Southern Illinois University Sustainability
This is the SIUC Sustainability Website, which contains info of current and future environmental projects, the SIU Green Fee, and links to various campus sectors. I'm a big fan of this site :)
Carbondale Food Works
Food Works is a local organization which seeks to draw attention to local and sustainable food in Southern Illinois. Currently, Food Works is working on a community food assessment, documentary of the local-food goings-on in So. Il., and a potential regional branding system for local produce. Links to the Food Works blog are found on this site.
Carbondale Neighborhood Coop Grocery
Regional or National:
Illinois Food Farms and Jobs Act
Farm Direct
This site is sponsored by The University of Illinois Extension. Through it, you can search for local farmer's markets, CSAs, produce farms, or specific commodities. What I find especially neat is that you can narrow your search according to mileage so that you can support the farmers who are near you. The site also contains helpful articles on the importance of supporting local farmers and what you can do to get involved as a consumer or an organization.
Local Harvest
This site is similar to Farm Direct, but it is at a national rather than state scale. Most of the farms on Local Harvest market their products directly to consumers. The website contains a newsletter and blog directly which is fun to browse through.