Hoarder of useless things

When i was a really young kid i was working beating for a pheasant and rabbit shoot. As i walked across a ploughed field i saw a small coin (its about 1cm across) and, as kids do, picked it up and shoved it in my pocket.

It was only when i got home i saw it was a German '10 Reichspfennig' minted during the second world war. As a nipper i couldnt help wondering if it was from a plane shot down? Not so far fetched to be honest as Rainhill is between Burtonwood airbase and Liverpool docks, both prime targets.

However it got there i still cant bring myself to get rid of it, but equally cant really explain why i keep it?