The time capsule, a welded-shut copper box, contains "records," according to an article about the dedication ceremony from the Mooresville Times (Thursday, Dec. 3, 1959, p. 1). These were presumably school records and probably also artifacts from the time (some possibilities include, e.g., a 1959 MHS yearbook, Wagon Trails; local newspapers; popular souvenirs from local businesses, churches, or organizations; school documents pertaining to the building's construction; the dedication ceremony pamphlet; and other historical items). But this is purely speculative; the only way to know for certain is to open the copper box. No mean feat, that. Those welds are pretty solid. Time capsules are intended to survive for centuries.
discovered (and uncovered) the cornerstone & time capsule