I'm coming to the rescue as I am a low level expert who can help on important matters such as this. Its a gilt button or a counterfeit coin that was gilt.
It could have been a button with a faux coin image. These tend to copy Roman Coins. However, although I see a Roman style head the metal type & lack of shank scar make me think some other type of object, like the top of a lid??
I cleaned it up and think y’all are right on it being button. I can make out the first three letters IMP. Was just curious as to whether anybody knows if it’s a military button or possible time frame it could be from?