Ahhh, I thought you'd meant Normandy beach. Now I see you're saying a farm in Normandy. If that's the case, then .... well .... WWII bullets are a dime-a-dozen. I thought if it was the fabled infamous beach landings (that get so much press as turning point , etc...) that they'd have "provenance". But for all the other untold miles across Europe, well, .... just a dime a dozen .
If you get away from the battle zones of WWII, then in those parts of Europe, you ought to find some old coins, eh ?