The John Roy Site in western Illinois, about 2 miles south of Clayton, preserves a pre-Columbian Woodland period village occupied from roughly A.D. 450 to 650 and five associated burial mounds. Its upland setting is unusual, since many villages of this era are found in river valleys, and it may reflect changing patterns of plant cultivation. Extensive seed deposits from the site provide evidence of developing agricultural practices during the Woodland era. Rare preserved woven artifacts also offer insight into the development of weaving and the organization of daily life within the village. The site was added to the National Register of Historic Places on May 22, 1978.