The bulk of the C. G. Robinson papers consists of the originals plus photocopies of Robinson's diaries, 1884-1890 and 1892-1895. Robinson recorded the weather daily, and he described his daily chores and seasonal activities, such as cider pressing in autumn and "sugaring off" in spring. William Rayner apparently raised prize-winning swine, which Robinson took to state fairs throughout the Midwest. Robinson's papers include letters from other area swine-farmers and a copy of the constitution of the Michigan Victoria Swine Breeder's Association.

Robinson's diaries contain many interesting facts relating to the Mason area. For example, he talks about the first Mason Fair in September of 1884 and the purchase of a new fire engine in July of 1885. He gives reference to Mason landmarks, such as the Baptist, Methodist and Presbyterian churches, the Rayner Opera House and Mead's flour mill. He mentions public social functions like church socials, free lectures and concerts and the Fourth of July Parade. The commercially printed calendar books which Robinson used for his diaries also contain printed calendars, postal and exchange rates, and U.S. voting records for these years. Robinson used the backs of these volumes to record his personal financial records, important dates and addresses.

The papers also include a letter written by Chan H. and Jean V. Robinson in which information is provided about the Robinson and Rayner families.