Oh, come on.
Throughout American history, the 'Indian Mounds' were the source of all kinds of weird ideas and theories, even from otherwise sensible folk. Sounds like you're propagating a couple of whoppers there.
Ol' Joe Smith had a few tall tales of his own along these lines. Those stories look particularly whacked in retrospect.
" Adena folk were unusually tall and powerfully built; women over six feet tall and men approaching heights of seven feet have been discovered. It would seem that a band of strikingly different people of great presence and majesty had forced their way into the Ohio Valley from somewhere about 1000 B.C. - Robert Silverberg
I've read of these too. Reports are too numerous to discount out of hand.
Okay, here's one of those great Ohio Indian Mound stories, and it's true. A professor at Georgia College who used to go on digs in Ohio Indian Mounds gave me a plaster cast of what appears to be either an amulet or coin that he found in layers that were dated sometime very early AD or perhaps late BC. The original artifact was very worn, but the figure on it is clearly a familiar theme on some Roman coins, a Winged Victory. FWIW, I'd be glad to post a photo of this plaster cast (if you can instruct me how to post a photo here!)