Black Rat Snake for sure, maybe Elaphe obsoleta obsoleta but I'm not sure of Latin name. Taxonomic discussions here: http://www.flickr.com/photos/clintg/3669346203/in/set-72157618140064842/ They shake their tail and let out a stink when threatened. I didn't smell anything but he sure did shake!
I have wanted a "wall pocket" for decades and never found one I liked in my price range. They used to all be antiques. This one, found in an art studio in Galesville for $20, is new. I love it. My cat can't knock the flowers over nor eat them now.