Across the U.K., in olden times, invaders like the Vikings forced people to bury their treasures and flee. These caches turn up on occasion and are subsequently turned over to authorities.
Today, if someone in the U.K. unearths rare gold coins in their garden, it technically belongs to the “crown”. The process for managing found treasure is laid out in the Treasure Act of 1996, anyone interested in reading the whole megillah can click this link. Treasure Act 1996 and absorb all of the wonderful legalese. Interestingly, the authority in charge of securing the treasure trove is the local coroner – Coroners Act 1988 (treasure).