Mockernut or Bitternut Hickory
There's an excellent book, Guide to the Trees, Shrubs and Woody Vines of Tennessee, that covers Carya species in Tennessee. Authors are Eugene Wofford and Ed Chester. http://www.amazon.com/Guide-Trees-Shrubs-Woody-Tennessee/dp/1572332050/ref=sr_1_1?s=books&ie=UTF...
This book has great images of the leaves of each hickory species and a plate (80) of the nuts in one photo.
This information is also available at no charge at the UT Herbarium website.http://tenn.bio.utk.edu/ Choose: Vascular Plants and search by common name or scientific name. Images on this web site are often the same images in the book.