In 1914, Oldroyd was recruited by the
California Academy of Sciences to classify and pack a portion of the shell collection of
Henry Hemphill, in preparation of the collection's transfer to the Academy following Hemphill's death. In 1916, she was hired by Stanford University, which had then acquired the Hemphill collection, to catalog the collection. A year later, Stanford purchased the Oldroyds' private collection and hired the Oldroyds as curators in the
Department of Geology, where they served for the rest of their lives. In the mid-1920s, the Stanford shell collection was the second largest in the world. They continued to collect shells in California and
Washington state, and in 1929–30 traveled the world, collecting and facilitating the acquisition of large collections upon their return. In 1922, Oldroyd was hired as a consultant by the
American Museum of Natural History in
New York City, where she spent several months studying and organizing the conchology collection. Oldroyd produced several papers, and is known for her major works:
Marine Shells of Puget Sound and Vicinity (1924) and
The Marine Shells of the West Coast of North America, a four-volume series published between 1924 and 1927. Oldroyd was a charter member of the American Malacological Union and served as its vice-president in 1934 and as honorary president from 1935 to 1940. ==Death and legacy==