In 1872, so the story goes, workers digging a hole for a fence post near Lake Winnipesaukee in Meredith found a lump of clay that seemed out of place. There was something inside -- a dark, odd-looking, egg-shaped stone with a variety of carvings, including a face, teepee, ear of corn and star-like circles. And there were lots of questions: Who made the stone and why? How old was it? How was it carved? To date, no one's been able to say for sure, and the item has come to be known as the "Mystery Stone."
full article at Boston.com
Image of the stone can be seen here
http://www.nhhistory.org/museumexhibits/my...ysterystone.htm