Frush was born in Iowa and moved to the Gulf Coast of Mississippi as a child. She began drawing as soon as she could hold a crayon in her hand; when she was ready for formal studies, she enrolled in art instruction courses in New Orleans. After additional training in Philadelphia and New York, Frush joined her family in Chicago, where she studied at the Chicago Art Institute under Charles Schroeder.

Frush opened her first studio in Chicago in the early 1940s. While she accepted freelance jobs, she also worked at the studio of Sundblom, Johnston, and White. By 1943, she had become one of the Gerlach-Barklow Calendar Company's most important artists, creating a string of popular series: Liberty Belles, Sweethearts of Sports, Girls of Glamour and Glamour Round the Clock. In 1947, her Aquatour series, a dozen pin-ups all located in aquatic settings, broke all sales records. By 1955, Frush had become a "hot property" in the calendar-publishing business, so it was only natural that Brown and Bigelow should seek her out. A year later, the firm published its first Frush pin-up, a horizontal picture especially done for "hangers" (large wall calendars with one print attached).

A vigorous and attractive woman, Frush enjoyed sailing, canoeing, swimming, and playing tennis, and she would often incorporate sport themes into her work portrayed in a crisp, straightforward style, her pin-ups and glamour paintings effectively captured the spirit of young womanhood. Her girls were wholesome and fresh, shapely but never overtly sexual. Somehow they were able to look both like movie stars and like the girls-next-door.

She sometimes signed her paintings with her married name "Mann". Her renderings were always done with great precision, capturing every nuance of a subject in an almost photo-realist technique.