I thought France but below the portrait the angle does not look quite correct ... https://en.numista.com/catalogue/pieces320.html
As with any identification the size would help us to help you.
If not France then maybe Italy or Greece also.
I also thought maybe Thailand or Luxembourg but cannot find anything similar; annoyingly
I have seen that portrait before but cannot currently remember where from.
Yes, it does appear to have the remains of a loop/shank attachment for a button- but I think it was originally a coin that was later repurposed for use as a button. This was not that unusual for people to do.