First of all, I am not a lawyer and this only my opinion as to the way the law works. Ask a lawyer if you're really concerned about accuracy. It's my understanding that usually, CW artifacts found on private land with landowner's permission are yours to keep. Technically, identifiable US army relics still belong to the US army. CS relics with the men's names , if they can be identified, belong to the family. CS relics with no ID belong to you or the homeowner. Practically speaking, these things seldom come into play.

Potential archaeological sites, especially Native American sites, are protected by Federal Law.Which is why pot hunting is illegal-if you find an arrowhead in a field I doubt that anyone will say anything unless its already defined as a protected area- If you are caught relic hunting on a protected battlefield your equipment and truck will be confiscated and you will be heavily fined and will probably do time- and don't forget, they have hi-tech detectors now that can pick up a metal detector being used in the area, even at night- law enforcement varies a lot from area to area- if you're really concerned, ask the police and park service in your area
I would like to know what the law is for artifacts found in the streams and rivers in Virginia- are they technically salvage?