One very interesting paragraph states:
"The Revolutionary War, however, brought on such a surge of counterfeiting — much of it provided by the British army — that the new United States government shunned paper bills in favor of coinage for decades. It didn't reconsider until the onset of the Civil War in 1861, when the federal government first authorized the printing of dollar bills called “greenbacks.”
Hence so many lost coins to be found from that period.