Have you seen the several family trees posted over on Ancestry.com? They may be part of rootsweb and would be free to view. The families of Phineas Mitchell's parents are extended back many generations, though none have the Yeaton surname. I don't have a bio on Phineas Yeaton to see if he may have made a name for himself in the same town where your relative lived, whom they honored by naming a child after him. I also did a quick check for any aunts or uncles that may have married into the Yeaton's, but did not find anything helpful. Good luck!