A lifelong history buff, Gary Laube of Southold decided to spend several hundred dollars to buy an 18th-century trunk at an estate sale in his hometown in 1992 because it contained a woven 19th-century coverlet made by a member of one of the town's oldest families. It was only when he got his purchase home that he discovered a textile balled up in the bottom of the trunk -- one that has proved much more historically and financially valuable than the coverlet and that quickly launched him on an ongoing historical detective hunt. What the 52-year-old Revolutionay War re-enactor and...