Here in Arizona, not too many houses have crawl spaces, but remembering back when I was a young one. I used to drop coins through a hole in the floor in the laundry room. This was about 50 years ago. We lived in the eastern part of the US at that time. I wish I could go back to the old house now. I'm betting there are quite a few coins under those crawl spaces. It might be a pain in the butt to get under some homes with not much room with your detector, but it could pay off big time.
John K
John K