Just joined but got the bug from my father in law. I am in Tuscola, Illinois about 20 minutes south of Champaign. Rayc50, it sounds like you are very close to my woods. We own the old town of Cleone which is just a few miles north of Martinsville.
I am in Ohio, but have you seenThomas Terry's US Treasure Atlas? He has one (volume 3)that includes several pages on Illinois It has some interesting sites in your area to look for neat stuff. Some of it is just legends, but some things are real and will lead you to something.