Mike,
Your stories are pretty good and also somewhat typical. We have found bones, and had a project stop until it was determined they weren't human bones, or historic, just old cow bones.
Like you, whenever we worked in Atlanta, we found civil war remnants. At Brookstone we found a natural rock bridge and waterfall over Pumpkin vine Creek near our proposed 14th green. We moved the green close for visuals, and also researched enough to know that the Army of the Ohio used that to cross the creek. Alas, when the subdivision was built, they ran the sanitary sewer right through it, dynamiting it in the process to a less aesthetic pile of rubble.
We found an old settlement house west of Ft Worth, TX) which had some great Danish pottery and plates. It conjures up images of a cowboy taking his more refined New England wife out west, probably despite her will. We have also found an underground fort, later determined to have been for protection against Indian raids. And, we tried to save the easternmost cactus in Texas (according to a botanist) but drift from our nearby irrigation was enough water to kill it.
One thing we find a lot in Texas is old oilfield pipes. Found one last week. Not on any maps, as it had a "blanket easement" allowing the oil company to have laid it anywhere they chose on what is now our property....unfortunately, they chose the new 15th fairway. They said they activate the pipe up to three times a year. Luckily it was dry when hit. This project is right on the western edge of the original Spindletop oil field from the 1920's, so we may find more.
Back in the old days, we used to find old coke bottles wherever we dug, but the frequency of that has greatly reduced over the years.
Probably the most interesting thing I ever dug up was in Poplar Forest, VA, right below the second home of Jefferson, built in 1806. We found he had used Tulip Trees, quite straight in growth pattern to fashion drain pipes. They would saw them in two, hollow/carve them out like a melon, and then use leather to strap the two halves back together to make drain pipes.