The papers in this collection deal mostly with Morrison's activities after retirement (1951) when he lived and had his nursery in Pass Christian, Mississippi. The correspondence (1924–[1945–1965], boxes 1–2) concerns plant breeding and the exchange or sale of seeds and bulbs, as well as information about his work and that of fellow horticulturists, publication of his National Horticultural Magazine and business of the American Horticultural Society.

There are six boxes of manuscripts, reports and notes. Also found here are Morrison’s libretto for Salve Regina (presumably copyrighted ca.1957) and certificates, letters of introduction and other personal documents (1915–1962).

Additional materials include sketchbooks and over 150 drawings in various media of Chinese and Japanese gardens and other scenes.