In 1901, using her inheritance, Nicholson moved to California, and soon opened a small shop in Pasadena, selling
Native American handicrafts such as baskets and weaving. She hired crafters to teach traditional beadwork and other skills; she rented space to local artists. She traveled extensively in the rural western and Southwestern United States, worked with local dealers to build her collection, and corresponded with East Coast collectors to sell the objects. She personally photographed and catalogued her holdings; she also built an extensive photographic record beyond the objects, especially of the
Klamath River people, with whom she had frequent dealings. She developed longterm relationships with some favorite crafters, well beyond ordinary business dealings: she paid for eye surgery for one ailing basketmaker, and paid college tuition for another young woman. Nicholson acquired artifacts for sale, but also for major museums such as the
Smithsonian Institution and the
Field Museum in
Chicago. She lectured about "the Indian" to churches and civic groups. In recognition of her expertise, Nicholson was elected to the
American Anthropological Association in 1904. As a member of the "Anthropological Society," she joined a tour group that visited horticulturist
Luther Burbank in 1905, in
Santa Rosa, California. In 1909, she was awarded a silver medal at the
Alaska-Yukon-Pacific Exposition in
Seattle, for a display of baskets and other artifacts. In 1924, she designed a new building for her collections, which (reflective of changing fashions) had begun to focus on Asian art. The architectural firm of
Marston, Van Pelt & Maybury worked with Nicholson to realize her vision. Her design, nicknamed the "Treasure House," borrowed elements from buildings she had seen in
China. The building was opened as an art gallery and shop in 1925, although the interior garden courtyard was not completed until 1929. The
Los Angeles Times regularly included Nicholson's gallery in listings of local art events. Notable artists whose work was presented under her supervision include Honolulu-based
Frank Montague Moore, Southwestern painter
Joseph Henry Sharp, Danish silversmith
Georg Jensen,
William Victor Higgins, watercolorist
Pop Hart,
Emil Fuchs, Dutch cartoonist
Gustave Verbeek,
Grace Hudson,
Agnes Lawrence Pelton, undersea painter
Zarh Pritchard, and Irish-born illustrator
Power O'Malley. She hosted an especially eclectic display of European
tapestries and Persian
pottery in 1928. Her building was deeded to the City of Pasadena in 1943, but she continued to live in her private apartment on the second floor until her death from cancer in 1948. ==Personal life==