A lot of people's conception of displaying American Folk Art might still be rooted in a very contextual idea of placing the pieces within the same historical style and setting. Nothing wrong with that at all, but there have recently been some great interior designers that find some incredible juxtapositions between say, American industrial with African tribal with Mid-century Modern.
One of those designers is Tyler Doran. His site, Heir Antiques, has some incredible objects for sale and a lot of examples of what he can do for your (or at least my) design-challenged interior. His shop is located in Providence, Rhode Island:
65 Eddy St.
Providence, Rhode Island 02903-1702
Pay him a visit if you're in the area!