I've run out of world coins to be sorting through and cataloging, and I've run out of state quarters to sort through, and I'm drudging the bottom of the barrel. I've been going through my box-o-crap - all the stuff that I thought was unidentifiable. I came across this very damaged coin that I thought had britannia on one side. Looking closely I could make out parts of the legend and I have narrowed it down to KM579.2 a Brittish half penny from George II (legend Georgivs) from 1746-1754. As I started looking at this, I relized that what I thought was damage looked like a big ol' 'A' on the reverse. I've played with the contrast a bit (but not much) to try to bring out the A. The area around the A is indented, so the A itself is at the same level as the rest of the coin. Is this a counterstamp, or just some wierd damage.
These are interesting, but perhaps never identifiable, I have a Mexican 2 Reales coin from 1773 which has a large P stamped on it, I have looked through the catalogs trying to find it with Phillipines, Puerto Rico, Pennsylvania etc, but so far it's identity remains a mystery. It is possible that some local merchant either in Britain or in the early American colonies marked said piece to keep it in circulation and try to keep it within their locale. Another theory that comes to mind is that it could have been made into some sort of crude farm pickers check, these were not uncommon in Britain during 16th-19th centuries.
