Like Mike, my Atlanta area courses had all sorts of relics. We had all the old civil war maps and overlaid them on current maps. It looked like the entire Army of the Ohio crossed Pumpkinvine Creek right at the 14th green at Brookstone. When we cleared the area, there was a natural rock bridge right where the maps showed they crossed, so it had to be the place.
We moved the green right over to the natural waterfall, but a few years later, when building a sewer line for development, they blasted it out of there, losing both natural beauty and history. Of course, we found lots of other battle relics.
For many years on other sites, it was typical to find old coke bottles or pottery, etc. We have found underground forts to hide from Indian attacks and other things as well.