Been reading up on old hoards of gold and silver.   In ancient times, before banks existed, one of the main ways people used to keep their wealth safe was to bury it.  These buried 'stashes' of wealth are known as hoards.   If this was done well, the treasure would have been hard or even impossible to find.   However this also had its drawbacks: If the person passed away, the secret of where their hoard was, would have gone with them.  
While this might have been bad news for the ancients, it means that there are still probably an amazing number of buried hoards.  Every so often, something is uncovered. One of the classics of recent times was the Staffordshire hoard, found in 2009, of over 3,500 gold and silver items, (around 160 troy ounces) estimated to be worth around $5M in total!
Another amazing recent example is the Stirling hoard of four gold torcs (solid necklaces) found by an amateur metal detectorist on his first outing.  Talk about beginner's luck!  The treasure was apparently 'seven steps' from where he parked the car.
Treasure that is uncovered is governed by a set of laws known as treasure trove.   These laws have undergone great changes recently.