The Mildred N. Beauregard Slide Collection contains 1,249 35mm slides, dated circa 1947-1971, of gardens and castles in England, Scotland, France, Holland, Switzerland, Sweden, Norway, and Denmark, as well as American gardens, photographed by Mildred Napier Beauregard. Some slides show tourist sites and scenes including skylines, rock features, waterways, boats and ships, and unidentified individuals. The collection also includes two slide viewers.
The Archives of American Gardens biographical information vertical file contains biographical material on numerous landscape architects, garden designers and horticulturists compiled from various published sources.