When in Greene County a number of years ago my brother and I searched many of the records and, alas, it appears Peter Harmon left no will. At least there are none on file there.
I descend from Peter's son George who married in Greene County to Nancy Neil. He is NOT the George Charles who is known as Mag the Grey Horse that married a Niel in Virginia; they are brothers. My George had children named Nathan, John Burton, Barthena, Nancy, Susanna and Cornelius Achilles Harmon. They all (except possibly Susannah) left Tennessee; John B. & Nathan to Illinois (their descendants went on to Missouri & Nebraska); Cornelius to Arkansas; Nancy also to Illinois; and Barthena to Wayne County, Kentucky and later (1851) to Ray County, Missouri and in 1861 to Lake County, California. She is my 4th great grandmother and was married to William Kelsay, who learned the gunsmith trade from his father-in-law George Harmon.
http://genforum.genealogy.com/harmon/messages/6255.html