Series I. Personal Papers consist of seven subseries. Subseries A. Correspondence contains over 2,200 letters dating from 1826 to 1892, and was largely organized by Wheatland himself. Letters are organized chronologically by date received; most were received within a month of being sent. Most circulars and meeting announcements are organized separately in the Other Organizations subseries (Series II. Subseries F.), though a few remain in this section. Correspondents include family members, J.P. Dabney, Dr. J. Farnum Jr., Reverend Joseph B. Felt, W. Knights Jr., George A. Perkins, William Prescott, E.S.L. Richardson, and Edwin Willcox among many others.

Subseries B. Journals is comprised of bound journals and loose pages written in a diary-like fashion. The journal entries from 1834 were written while in England. Subseries C. Financial Papers contain mostly receipts, some insurance policies, and a few tax documents. Subseries D. Speeches include addresses made to members of the Essex Institute and a speech on Salem Schools, possibly to the Salem School Committee. Subseries E. School Papers consist of compositions and math worksheets from high school, notes taken during Professor George Ticknor's lectures on the history and criticism of French Literature at Harvard, and the constitution of the Linnean Society of 1832, which is a society to assist its members in the study of Natural History and expansion of their personal collections. The constitution was approved by twelve students and named Wheatland as the Corresponding Secretary of the society. This subseries also includes invitations and correspondence from Harvard to its alumni. Subseries F. Notes on Topics of Interest is made up of the copious notes Wheatland made over the years while reading, researching, or attending lectures. The topics include his interests in biology, natural history, medicine, local history, as well as his classmates at Harvard. Subseries G. Other Papers include Wheatland's professional notes on patients as a physician; invitations and lecture cards; catalogs of his personal library and two unidentified libraries; drawings; ticket stubs and programs of events; and two copies of a history of Essex County institutions written in Dr. Wheatland's hand.