Check out this amazing free campsite (near Sedona, AZ!) I found using the Frugal Shunpiker's guides.
These guides -- available for the six "most scenic states" Texas, New Mexico, Arizona, Utah, California, and Colorado -- are packed with the prime spots for free dispersed camping.
Of course, you can find many free campsites via Freecampsites.net and a few smartphone apps... but naturally those who post there -- including myself! -- don't give away the BEST of the best sites. But these books do.
For example, the campsite in this video is known to locals, but as far as I've seen, it's not posted on any public websites or guides. It's simply not like anything else you'll find anywhere, including this area. It's a singular "gem" campsite -- in an area FULL of amazing campsites -- that no one but locals are supposed to know about.