1689/92 - Tin William and Mary Farthing with copper plug to prevent forgeries
As can be seen it is in poor overall condition which is to be expected, but possibly more room to improve appearance with some careful restoration.
The tin issue had a copper plug running through the centre to try and avoid forgeries. Due to tin being susceptible to tin rot they are rare. Tin rot occurs when tin is kept at a low temperature for a length of time, and is actually transformation of tin to a powdery allotrope of the element. This is why the edges are often nibbled in appearance. The date and an inscription was on the edge.
Copper W&M farthings were minted in 1694 only.