If you have legal access to the land you really should go buy a good metal detector! There are so many things that will be lost forever if they are not found.
There are even videos on U Tube about metal detecting in Europe. Pulling Germanrifles (not usable), helmets (worth a ton of money!)personal effects, and the list goes on! One guy even found a buried tank.
I have a chance to go to Virginia and to legally detect where the The Wilderness Battle was. I would be happy if I just dug up a Confederate bullet!