My line of Pannells goes like this: my grandfather was James Arch Pannell, his father was Mathias Madison and his father was John Pannell. James Madison was the first son of John and Nancy McAnally Pannell, then of course you know that he was the father of Andrew Adolphus Pannell. So James Madison was my great-granduncle, Andrew Adolphus would be my 1st cousin twice-removed and then Fred and Grady would be my 2nd cousins once-removed.Hope this didn't confuse you any.
It would be very interesting to find out about Fred and Grady... so I am guessing there was a mine explosion? Was it in Blount County?
I am sure Oak Hill Cemetery has grown since you were there last for it is quite large now.