Born in Colborne, Northumberland County, Ontario, the only surviving child of William Harold and Ethel Nobles, she spent her early life at the family farm in Vernonville.
[3] Mildred's family relocated to Regina Saskatchewan due to her father's poor health, where she attended public schools and the Collegiate Institute.
[1] She dreamt of working at the Central Experimental Farm in Ottawa so she applied for a summer student position.
[2] Nobles undertook pioneering research in identifying wood-destroying fungi and was eventually established as a world authority in this field.
[1] During the 1940s and 1950s Nobles' lab was the centre for identification of cultured wood-destroying fungi for the Canadian Forestry Service.
[2] In 1965 Nobles published a multiple choice key to replace her 1948 publication to further simplify the identification of wood decay fungi species.