Nannie Knowlton Barnum was the author of numerous poems, including a collection titled Musings, published in 1931 by The Christopher Publishing House, Boston. Her photograph (taken at the age of about 70 years) appears in the frontispiece of the book. According to the description given on the back of the dust cover, some of her verses had been accepted for inclusion in the Twentieth Century Hymnal, published in 1925.
In the 1940 US Census she was enumerated as 81 years old, widowed and living alone in Youngstown, Ohio, in a house that she rented for $35 per month.