lost and found

or lost-and-found 

noun

1. a room in a public place for items left behind and from which the owners may retrieve them.

Example Sentences

They dress in clothing from the flophouse lost-and-found and are groomed with a hacksaw and gravel rake.

From The Daily Beast

David, still very courteous, suggested that possibly it had been picked up and taken to the lost-and-found desk.

From Project Gutenberg