There's one set that I recommend first and foremost, regardless of where a person lives. The Bell / Perino guides. They are basically a compilation of typological information from all over the United States. The best part is that they are affordable ($64 for all 4, shipped). There are regional specific typology books that are great for certain areas, but no other that cover the U.S. are as accurate....so far. Buzz, I would make sure to join the MAS, they do have some good publications.
I have a TON of reference material for MO and the Ozarks, some of it was very hard to get and I wouldn't trade them for anything. There is a decent book written some years ago called "artifacts of the current river" or something like that? I forgot the name of the author, but was really impressed with the typology accuracy for the area. One other you will want is Don Dickson's book "prehistoric bluff dwellers of the Ozarks".
Overstreet sucks, unless you just want a picture book of pretty points. The misinformation in there has really screwed up a lot of folks.