The bulk of the collection consists of handwritten essays and speeches by Jessy Quinn Thornton, a lawyer in 19th-century Oregon known in his life as J. Quinn Thornton. These writings cover a variety of topics, such as the legal profession, education, Oregon history, the Oregon Bible Society, temperance, and Thornton's own autobiography. Some of these works have words or lines crossed out, indicating that they may have been drafts. The collection also includes a bound volume with typescript copies of these writings, possibly compiled by Thompson Coit Elliott.

The collection also includes a scrapbook of newspaper clippings compiled by Thornton, made from a repurposed printed government report. These clippings include letters to the editor, the text of speeches, articles about Thornton and Oregon history, and reviews on books about Oregon history. An inscription in the front indicates that Thronton gave this scrapbook to Samuel A. Clarke, and the scrapbook also includes brief handwritten commentary by Clarke's daughter, Sarah Clark Dyer, that she wrote in 1929.

Other materials in the collection include: A handwritten historical sketch by an unidentified author about John McLoughlin's departure from the Hudson's Bay Company, which notes that Thornton worked as McLoughlin's legal representation; a receipt from James Moffet for $1,000 for a lot in Oregon City, Oregon; a complaint that Thornton lodged in court against Justus Wells and Edward Morgan; a letter from Samuel R. Thurston, concerning accusations that Thornton had made against Thurston; a printed pamphlet by Thornton about the history of real estate in Salem, Oregon; a typescript of a poem that Thornton had written in Cornelia Spencer Greer's autograph book; and a printed new year's poem addressed to the patrons of a newspaper, The Political Examiner, probably based in Missouri.