I havent seen a nickel like this one before, it seems that the right hand side of it was minted too deep. See what you think, take a look. http://i235.photobucket.com/albums/ee157/l1melite/PICT0360.jpg http://i235.photobucket.com/albums/ee157/l1melite/PICT0362.jpg http://i235.photobucket.com/albums/ee157/l1melite/PICT0361.jpg
You've got a slight horizontal misalignment of the obverse (hammer) die, along with a finned rim. The die was slightly tilted down on the right side which raised the effective striking pressure in that area. As a result, coin metal rose into the gap between the die neck and the collar, creating a vertical flange at the rim/edge junction that we call a "fin".