No clue. The obverse has the portrait of the king, and from around the 12 o'clock position going clockwise should be the king's name, then a bunch of abbreviations in latin for titles etc. Yours seems to have the lettering IACO on the obverse that I can make out maybe? That could be for the name Jacob? Still doesn't really tie in to a king that would be producing this kind of sterling penny that I know of. Decipher the rim text on both sides and you should have a king and mint. Keep researching and comparing.