Don't trust the sprinkler head locations; they are meaningless. Don't trust do it yourself metal detecting because I tried and there are so many false positives. The builders bury their trash everywhere. You are supposed to trust your plot plan but then again, the builder can get away with anything as long as it looks close.
Get a real surveyor to tell you where the lot corners are based in the Datum used for your street. Then make sure you see if everyone around you did or will conform to the rules when adding cement molded curbing, the stack wall builders and landscaping guys will tell you anything to get the job and don't contact the villages. That's why they can start in a couple of days. 8
If your neighbor's stuff is on your property, take a breath, evaluate how bad is the infraction, and if you can live with it in peace with the person, then let it go.
There are some places in our neighborhood where there is no room for the riding or even push mowers to get through. How did that happen?