Green Split Peas or Whole Peas are the dried seeds of the pea plant. The peas are left to grow, the seeds fill the legume and the pods are allowed to dry on the vine. At harvest time, the dried peas are saved to be used dried in soups and sauces. Dried peas have been an important food source for over ten centuries. Carbon dating  peas found at archeological sites in Thailand have been found to be from about 9750 B.C. With the invention of modern refrigeration and freezing, dried peas are not as popular as before. However, in many cultures, dried split peas are still enjoyed in many delicious ways, such as the traditional split peas cooked with ham bones or hocks. 

Look for peas that have good light green color, and have no defects, stones or bug infestations. Dried Split Peas can be purchased by the pound, 5 lb. bag, 25 and 50 lb. bulk sack. 

Here are some pea picking sites:

http://www.cafecreosote.com/Recipes/Soups/VegetarianSplitPea.shtml

http://www.neosoft.com/recipes/soups/split-pea11.html