MERRY HILL, N.C. — Under a blistering sun, Nicholas M. Luccketti swatted at mosquitoes as he watched his archaeology team at work in a shallow pit on a hillside above the shimmering waters of Albemarle Sound. On a table in the shade, a pile of plastic bags filled with artifacts was growing. Fragments of earthenware and pottery. A mashed metal rivet. A piece of a hand-wrought nail. They call the spot Site X. Down a dusty road winding through soybean fields, the clearing lies between two cypress swamps teeming with venomous snakes. It is a suitably mysterious name for a...