This brings up something I have thought of lately. What happens to dirt that gets piled up when they grade property. From looking at some large scale developments, around here, they seem to pile it on one end of the property. Then, I assume, they use some in landscaping etc. However, when they get to the area where the pile is, where do they take it to dump it.... What if you have a landscape project in your yard and need some soil for a garden, to build a burm or for some other need. Or, when they build golf courses and build up the raised greens....
My point is that I assume it is taken somewhere, where landscapers and contractors, know where to get it if they need it. I seem to recall that some does go to land fills to help burry the garbage. I don't think though, that the best top soil, where most coins, jewelry and valuables would be, would end up there though.
So, there might be some logic, even if your house, neighborhood and yard are on modern land and you were the first occupants of the home, search your yard anyways. After they finsh building your house, and put down a firtile layer of top soil to lay the grass on, or build gardens around the property... they might take some dirt from somewhere that could have some valuable treasure from far away.
For kicks, the other day, I took my detector out in our yard. Our house was built in the 1950s. The neighborhood was plotted out in about 1920. We are the second owners of the property, since the house was built. I can't imagine much being out there but, when searching the yard, I was getting hits everywhere. I didn't dig any because it has been so dry lately and because of the dog poop and all. But, it is getting intriguing. Perhaps, a little later when it gets cooler and a little wetter. Then I won't have to worry about damage. At least not for long before snow falls and covers it all. Then, next spring, when they power rake and seed, it will all get fixed.
One thing that I do recall my older brother saying, I was very little when we moved here so I don't remember, He said that there was a big rose garden in the middle of the yard when we moved in. My other brother told me that he and my older brother had taken my old metal detector, I didn't even know it ever worked. I never found anything with it other than a doorknob when I was away at school.
Anyways, they had taken the older detector and had searched the yard, just for kicks. The only thing they found was a pruning clippers. Probably lost in the rose garden.
So, when they filled in the garden and sodded it over, Who knows what might have already been there and what might have been brought in as they redid the yard. Also, some years ago, we had a drainage problem where water would get into our basement. They built up some of the dirt around the house, poured a new patio and pitched the yard out away from the house. Some stuff could have been brought in, in dumptruck loads of soil.
With my luck though, all these targets will be BBs or pellets from when we would shoot around the yard or nails from building the addition onto the house. Some have been IDing as coins at about 4-6" though. Seems a little promising. Being that we moved here in about 1964, there could be some silver potential.