treasure trove

 

noun

[mass noun] English Law
  • (abolished in 1996) valuables of unknown ownership that are found hidden and declared the property of the Crown: there’s a chance that the coins could be treasure trove
  • [count noun] a collection or store of valuable or delightful things: your book is a treasure trove of delights

Origin:

late Middle English: from Anglo-Norman French tresor trové, literally 'found treasure'