Hello FL --
Welcome! You have an interesting piece. It looks like a modern imitation of an old gold coin from the German State of Prussia. As best I can tell, the inscriptions read FRIDERICVS BOROSSORUM REX and ARGENTEA MONETA. These point to Friedrich II, the Great, of Brandenburg Prussia, 1740 to 1786. The picture I posted here is of a valuable gold coin of Friedrich II. It has a faint resemblance to you your piece -- the closest I could find in our database.
But yours is a modern look-alike, worth very little. There is a faint possibility that it is made of gold. Take it to a jeweler to find out. If it's gold, it's valuable. Otherwise, it is an interesting conversation piece.