Small denomination silver coins have been packaged in Maundy Sets and given out during church services on Maundy Thursday, the day before Good Friday, the day Jesus Christ wss crucified. This has been going on for centuries. The sets left intact are in uncirculated condition, or close to it, so that makes them quite valuable. You can divide, very roughly, the 4-coin set value by 4 to get a single coin value.
The general values of 4-coin Maundy sets (all the same dates) goes roughly like this:
Before 1700: $800 and up
Before 1800: $500
Before 1840: $400
Before 1900: $300
After 1900: $200
These are catalog values and very approximate. There is a modern date which is exceptional:
There is also another twist. Proof Maundy coins carry values about 3 times higher than normal strikes. Proof coins are minted with specially polished dies and are treated with extra care during the minting process.