I may have misspoke somewhat about the easy and cheap part, but it is a very cost effective alternative to going to remote places and mining them out with human labor, such as that diamond crater in Siberia that was all the rage for a week maybe a year ago. (google if you have other questions about that)
By inedible cultivars, I mean species of plant that are not produced for human consumption (in a field to table, direct manner) and do not taste very good. Just cause I like you bear, I will even link to Monsanto's website, where they even specify what certain species are to be used for.
http://www.monsanto.com/products/Pages/processor-preferred.aspx - This is for ethanol production, does not taste like corn bought at the store.
http://www.monsanto.com/products/Pages/corn-seeds.aspx various corn seeds, the uses, etc.