Richards was an admirer of Dr. Hansen and often stopped to visit him in his office. After Dr. Hansen's death in 1950, David asked for and received, permission to keep a few souvenirs and then dug through the trash filling several boxes with papers of historical value.

This collection is composed writings for the South Dakota Agricultural Experiment Station in the form of bulletins and circulars, manuscripts for articles and publications that include Hansen's notations and corrections, correspondence with friends, colleagues, and customers interested in ordering seeds or rootstocks. Also included are catalog descriptions of plants to be included in seed catalogs, transplanting cards on which researchers will find records of planting and transplanting of plant hybrids, and research projects and reports to the Agricultural Experiment Station and material related to the South Dakota Horticultural Society.

Some items of note are collected Russian publications, seed catalogs and Seeds and Plants Imported published by the U.S. Department of Agriculture which list the plants and seeds imported by Hansen. Researchers will also find some material related to Hansen's travels.

The publications and manuscripts by Hansen related to many different horticultural topics: apples, crab apples, apricots, cherries, currants, grapes, pears, plums, plums, roses, roses, alfalfa, trees, plant genetics and breeding.
Researchers will also find clippings related to Hansen and photographs.