This collection includes police reports, official correspondence, notarized documents, and farming and grazing leases relating to the Yakima (Yakama) Indian Reservation and Fort Simcoe in the State of Washington. It also includes postcards, envelopes, photographs, and two artifacts. These materials were acquired from Fort Simcoe on April 22, 1934 by Dr. Donald H. Clark, Chief Forester and second in command on the Yakama Indian Reservation circa 1930 to 1935.

Most of the correspondence relates to criminal matters and social and economic issues such as murder, trade, theft, marital problems, etc. The envelopes are addressed from various agencies in the Department of the Interior, including the Indian School Service, the Census Office, the United States Indian Agency, and the Office of Indian Affairs. They correspond with letters present in the collection, however not all were paired together when originally processed.

The photographs included in the collection depict a bear named Cactus who was rescued and housed at Signal Peak, Washington after his mother and sister perished. The photo captions explain that Cactus had several canine companions and was the mascot of Signal Peak before he became too large and was transferred to a zoo in Yakima. Additionally, the photographs portray the year-round home and 1934 Ford automobile belonging to Donald H. Clark when he worked on the Yakama Indian Reservation. The two artifacts are a beaded watch fob and a deerskin baby doll on a cradle board, both made by the wife of the Yakima Reservation's Chief of Police and given to Donald H. Clark as a token of friendship in circa 1935. Pasted on the reverse side of the baby doll is a typed explanation by Donald R. Clark. The collection also contains a letter and a partial inventory provided by Donald R. Clark when he donated the materials in 1997.