This collection consists of letters, diaries and financial notebooks of various members of the Mattoon family. Most of the early letters (1835-1859) were collected by Charlotte B. Sweet Lindley, who was related to Nancy Agnes Amy Lindley Mattoon by marriage. Much of Mrs. Lindley's family lived in New York, and most of the early letters relate to this state. There are scattered letters from Michigan in the earlier years, and a large number of letters from Shiawassee, Clinton, and Alcona counties beginning in 1851. These Michigan letters contain limited information on agriculture and general life in the area.

The most informative portion of this collection is the correspondence relating to the Civil War. Letters from Gershom Woodruff Mattoon and his brother George Pearson describe their enlistments and the movements of their regiments. A letter from Gershom dated December 4, 1864 tells of the burning of Loudon County, Virginia by Union forces in retaliation for raids by General Mosby. His mother's letter of April 27, 1865 tells of the death of Abraham Lincoln. A letter from Cambric, New York dated April 24, 1864 describes how a neighbor of the family enlisted and then deserted after receiving his bonus; and a letter from another soldier dated July 12, 1864 tells of the horrors of the Wilderness Campaign during that summer.

Gershom Mattoon remained interested in veteran's affairs and corresponded with old army comrades long after the war (1890-1910). Some of these letters shed additional light on the war. Letters from Samuel Smith (1900) describe conditions in Confederate prisons. A letter dated October 16, 1905 tells of Sheridan's famous ride from Winchester, and a letter of December 19, 1908 describes the battle of Cedar Creek in Virginia. A final letter of interest in the collection is dated March 13, 1881 and relates the opinions of an old army comrade in Virginia on race relations, politics, Lincoln, and Jefferson Davis.

This collection also includes diaries, financial accounts, and expense notebooks containing information on daily life and costs of goods and labor during the years indicated. One of these books contains notes spanning the years 1727-1908, and is interesting as an example of the art of the early bookbinder. A financial record dated 1918-1920 was kept by Mildred Mattoon during her years at M.A.C. (now Michigan State University). Additional information concerning the Civil War is recorded in a bound book of family and regimental records. Rough notes, speeches and writings by Gershom Mattoon, as well as newspaper clippings he collected to preserve the history of the war round out the collection.