Nearly 400 acres of open land that once was planned for offices and parking lots in Coyote Valley, a scenic rural expanse on San Jose’s southern edges, is moving into public ownership to become part of an open space preserve for wildlife, flood control and recreation. The Peninsula Open Space Trust, a non-profit environmental group based in Palo Alto, is selling the 376-acre property, known as Laguna Seca, for $16 million to the Santa Clara Valley Open Space Authority, a government agency in San Jose. That’s a discount: the land trust, commonly called POST, bought it for $21 million five years ago. … The property is valuable not only as a wildlife corridor for deer, coyotes, mountain lions and other wildlife, but also as a natural flood control basin, where water from Coyote Creek can settle in big storms and seep into the ground, rather than flooding neighborhoods and roads.