You may be right, but I was quite aware of the problem of being observed and took precautions to avoid it. That's actually easier to do in a small town than a city. For example, it was the County Seat and the Court House was located in the middle to town. It was open at all times -- you could go in at night and no one was ever around (except inside the sheriff’s office). There were several places to hide coins that would seem completely secure and you could be sure no one was watching. There are many similar examples. So, I don’t think I was seen hiding them very often.
But, the suggestions given in this thread may well be the answer. Everyone knew me and my folks. If I’d put the coins in an envelope with my name, saying they were mine “Please don’t remove,” I have a hunch they wouldn’t have been taken often.