Throughout the UK farmers ploughing fields, archeologists doing research and amateur treasure hunters just looking for coins occasionally unearth important treasures (such as the Sutton Hoo Treasure) of immense scientific and financial value.
Because of the legal system in the UK there had to be a determination of whether the property was lost (e.g. dropped on an ancient battlefield) or just buried intentionally (e.g. at a burial or simply to keep it safe). In the former case, the finder can keep it and become rich--in the latter the property is Bona Vacantia and belongs to the Crown (and generally goes to a local or national museum).
The local Coroner was the official who decided whether the property was the property of the Crown or could be owned by the finder.
This whole regime was swept away under the Treasure Act 1996 which now lays down a statutory regime for dealing with found Treasure.