The Trustees of Reservations announce Open House Day on Saturday, May 31, from 10 a.m. to 2 p.m. at the following historic homes: Naumkeag, 5 Prospect Hill Road and the Mission House, 19 Main Street, Stockbridge, Mass.; the Ashley House, 117 Cooper Hill Road, Sheffield, Mass.; the Folly at Field Farm, 554 Sloan Road, Williamstown, Mass.; and Bryant Homestead, 207 Bryant Road, Cummington, Mass. The open houses and tours are free. For information, call 413-298-3239 extension 3013, or email [email protected]