where civil war soldiers camped

This is by all means not a complete list, just a couple of places to search.

If they camped near the battle field, you may want to look on the back side of a ridge overlooking a battlefield. The defending soldiers wanted to be close to their earthworks where they could get to their positions in a few minutes.

On march route camp sites you should usually look on higher ground between the march route (or road) near a creek. Water for the men and horses was always needed to be close by.