There is no simple description on definition of what a folk art is, but here goes.
1.Stuff made by the folks down at the art store
2. Outsider Art
3. Anything made from local materials and is usable or unusable whichever may be the case.
4. Fish Decoys can be folk art.
5. Fish Decoys are folk art.
6. Duck, Goose and gunning bird decoys can and are folk art.
7. the lists goes on an on and on.