That's a jeton, Robert. Jetons (IETTON) were tokens (not coins) used during the middle ages for counting. Our general page on jetons, with pictures, background, approximate values, and web references, appears at this link.
Your jeton bears inscriptions for Friedrich (FRIED) Wilhelm (WILH) III king (KOE) of Prussia (PREUSSEN) who reigned from 1797 to 1840. This gives an idea of the date of your piece.
The jeton in our picture comes from Munzenversand Hardelt in Kaiserslautern, Germany, where it is on sale for 15 euros, about $19 US dollars. The Hardelt piece is in good shape. Jetons with more wear, or with damage (like a hole), will be worth far less.
CoinQuest thanks Munzenversand Hardelt for use of their coin image.