My 2cents on wild camping:

The Straight Dope On Wild Camping | Adventure Vagabond

It's a little known fact but it's free to camp in National Forests.

ask a farmer
 

i found camping around the states if you just ask a farmer if you can camp on their land, and explain you are a traveler - not looking for somewhere to squat - and are respectful (no asinine noise or trash, no ruts left, no disturbed crops/livestock), they have no issues w it. and sometimes this also gets you an amazing home-cooked meal!... if you do this though, at least send a postcard or find someone to thank them.... couchsurfing is excellent for travelers. but it is more for cultural exchange, not just somewhere to sleep for the night. csers are usually extremely helpful, so do not take advantage. if you are just wanting to sleep and run, camp... if anyone ever needs a place in mo to camp, look up david key in louisiana, mo. and tell him his daughter said he would let you camp on the farm.