The heart of the Smith-Frederick papers are the letters written by Clementine Smith to her husband, then absent in California. The letters were written at Eddyville and Oskaloosa, Iowa in 1850. (Sidney Smith left Oskaloosa for Council Bluffs around May 1, 1850.) In this correspondence, Clementine attempts to give her wandering husband a full account of family and local news occurring in his absence. While there is some personal material in the letters, there is a great deal more general interest including political affairs, activities of common friends, doings of the "California widows" (some of whom were having children in their husband's absence), commencement of a newspaper in town, area activities, and social events. Her letters reveal her anxious but resolved state of mind and reported to her husband news that others received from Iowans on the Plains or in California.

In addition to these letters, there is also one from Clementine to her mother with a postscript from Sidney Smith (September 14, 1855). An 1865 letter related to the service of Lt. Smith, Regimental Quartermaster, 18th Iowa. A draft written by Sidney Smith in 1882 concerns the service and wounding of a private from the regiment. And finally, a letter addressed to "Brother" from "Bachelor's Lodge," Augusta, Iowa, December 17, 1843, is probably from Smith's older brother Charles N. Smith. In it he tells of life in the Territory and immigration to it from Ohio.

Also included in the collection is a letterpress copybook written by Electra C. Frederick Owen, containing letters addressed to her "Dear Cousins" (Hannah and Benjamin Frederick) in Ohio. Written from Oskaloosa at various times between January 1850 and April 1859, the letters are principally philosophical and religious in nature, but also contain valuable information. Subjects include recollections of girlhood life in Ohio; impressions of the death of her brother LaFayette at Monterey, California, in 1848, while a soldier; her mother's death at Oskaloosa in 1857; the death of her brother William at Oskaloosa in 1858; her father's purchase of a nearby farm and his remarriage; and local affairs. This volume also contains genealogical records.