Hi. As a Brit and mentor:
There is a rhyme that goes:
"Finders keepers, loosers weepers".
In the UK, when I was last there anyway, if you found something and handed it in at a police station, the person who lost it had, I believe, 3-months to claim it. If they didn't, you could go back to the police station and they would hand it over to you as your official property (other than items such as keys and any other item that, whilst not having any traceable name etc on it, would be inappropriate for them to hand over.
There may be some people who bypass a certain part of this process and, on finding something of value, may just say: "Ah, well. Finders keepers, loosers weepers"!
Hope this helps in your understanding.
Student or Learner