Photos of the other side (even if it's mostly worn away) please!
And most, importantly, please don't forget WDM:
Weight
Diameter
Metal
From what I see though, I'm fairly sure I've seen that pattern on some French feudal coins or perhaps on period jetons. Just not sure from where; and I could still be wrong, though.
I'm now absolutely certain it's French in origin; swirly pattern visible there looks like the designs found on pre-Louis XIV (roughly) French coins like this one (obviously not this one, just an example):