The obverse inscription "rosa sine spina" translates as "rose without a thorn" and is typically associated with 16th century British coinage. I believe what you have is one such issued during the reign of Elizabeth I.
Do not clean this beauty except for simple non-tap water and air dry to remove some of the grit. Don't use any chemical and don't rub. Really a lovely example. I'm nowhere near my books so that's all the help I can give.
I might suggest relisting the topic under a GB question.