I've been in touch with others working on my Walker line, they taken it back quite a few generations and I don't see Pinkney as a surname. For some reason it seems to be very common in the South as a given name or surname. Probably some well known preacher man or politician with that name. Like Greenberry, another common name for men in the South.
You'd think with all our Southern lines we'd have a match somewhere.LOL