NAL Digital Collections

If you have any interest in the history of American agriculture, you'll no doubt be fascinated by the digital collections from the National Agricultural Library: 

http://naldc.nal.usda.gov/naldc/home.xhtml

Publications available include, among others, the Historical Dietary Guidance Digital Collection, the Organic Roots Collection, and the USDA Pomological Watercolor Collection, which presents paintings, drawings, and models of plant specimens created between 1886 and 1942.  All collections can be searched simultaneously or browsed individually.  So, if you're a hayseed from way back, now you can easily find historical publications about actual hayseeds from way back.