Here is a Charles II Crown with what looks like a stop below the bust. It has a very clear edge "VICESIMO NONO". I know it's in terrible condition, but I felt sorry for it and thought I'd "rescue it", because it looks so interesting. Pity about the Reverse! - I only paid £14.64 for it, so it's not bad. I bet someone has seen a similar one!
I wish people would stop polishing coins, though! - I always wipe over any that have been cleaned with a damp cotton bud. I wipe them again and put them in a brown envelope. If you don't get the desired re-toning the first time, keep doing it until you do. It's an ideal example to try this kind of thing on!