Here are two useful maps for natural builders. The map from Natural Homes.org shows locations of natural homes. Actually there are thousands of homes not shown. As a rough guess I’d say for every house shown, there’s probably another 100 not on the map (and far more in some areas). Most people don’t publicize their homes, because they don’t want hordes of people knocking on their door unannounced. And it would be impractical to identify adobe homes, for instance, where practically everyone lives in them.
Another useful map at Earthship Pockets of Freedom shows counties where “acquiring permission to build is not a bureaucratic expensive mess”. This is another good step forward, although the map lacks clear definitions about what constitutes a Green County.
You might also be interested in Terry Herb’s book on No Building Codes.