The Plymouth Congregational Church records contains historical records created and maintained by the church from around the 1910s through 2010s. The collection contains (but is not limited to) church records on baptisms, weddings, and funerals; architectural drawings of the building and grounds (including the Little Schoolhouse); church bulletins; educational materials; organizational records, including minister files, records maintained by church organizations (eg. Music Committee, Women's Fellowship Circles), and information on governance; ephemera related to events; press clippings; scrapbooks, photographs; and sermons and memorial tapes.

The Finlay B. Matheson collection includes more than 2,411 photographs; 112 maps, surveys, and architectural plans; and 13 books related to William John Matheson and his immediate family. Estate documents and other documents containing historical and biographical information pertaining to the Matheson family and their various business ventures can also be found within this collection, as well as drawings, postcards, and some of the first aerial view photographs of Key Biscayne, Coconut Grove, the Miami River, and the Florida Keys. Florida's landscape during the early 20th century is captured throughout the various albums and scrapbooks and attests to a more leisurely lifestyle before the advent of skyscrapers and multi-lane highways. Furthermore, the collection provides an in-depth glimpse into the burgeoning social life of early inhabitants who gathered at the Biscayne Bay Yacht Club.