Foumd this working the wet sand. I cleaned it up some and it shined up just lime silver but it stick to a magnet. No markings other than a possible "j" on the from that could just be a scratch. Tje shank appears to be of an oldwr style button. Any ideas?
I'll be honest with you... my butt clenched when I read that you took sand paper to the corrosion.
Stylistically it looks to be 18thc, but it also looks to be made of pot-metal as opposed to tombac.
Have to agree with Smokey that it's more likely to be mid-20thc modern.