Hey JM,
It could be a Turkey tail, beaver tail or a modified Adena. If you could mentioned where you are at or part of a state it could help and narrow it down to a specific type. What tribes existed in that area? Any known camps or villages, or could this be a drop in the field? Just curious,
~Stan~ aka ~Z~
***Update***
Sorry for the above post I went to the book schelf to double check and these folks are correct and I am mistaken. While I could remove the above, I prefer to admit when I make a mistake.
Best of luck and Merry Christmas
~Z~