treasure trove 
noun [mass noun] English Law
1(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...
- If it is, it may be declared treasure trove and become the property of the Crown - but at least you'd be compensated.
- I just take them to Colonel March, the coroner, tell him where I found them and he rules they're lost property, not treasure trove, and gives them back to me.
- Last month a stunning 13th century gold stirrup ring, set with a sapphire, that he uncovered at a different site near the town, was declared treasure trove at an inquest at Chippenham Magistrates Court.
1.1 [count noun] A collection or store of valuable or delightful things: your book is a treasure trove of delights...
- Down the steps here into a treasure trove of stores selling gifts, leather goods, fun jewelry, men's and women's accessories, ties, belts and shoes.
- The present book breaks new ground, unearthing a treasure trove of visual delights as well as a profusion of new information.
- The painstaking effort, neatly tied with pink ribbon, with its affectionate dedication to her parents in red crayon on the cover, is preserved in the Royal Library, a treasure trove of books and manuscripts housed in Windsor Castle.
Origin
Late Middle English: from Anglo-Norman French tresor trové, literally 'found treasure'.