Elinore Pruitt was born in 1876 in White Bead Hill, then a settlement in Chickasaw Nation, Indian Territory and as of 2016 is an abandoned township in Garvin County, Oklahoma. Her father died in the late 1870s on Army service near the Mexican border. Shortly afterwards, her mother, Josephine Courtney Pruitt, married her husband's brother, Thomas Isaac Pruitt, and bore eight more children. Elinore was educated for a few years at Pierce Institute near White Bead Hill until that grammar school closed in 1889. In 1893, her mother died of complications from childbirth, and in 1894, her stepfather died in a work accident, leaving the orphaned Elinore responsible for her younger siblings, with only her grandparents available for support.
Around 1902, she married Harry Cramer Rupert, then 48 years old. He died in a railroad accident before their daughter Mary Jerrine was born (February 10, 1906, reportedly in Oklahoma City). She then relocated to Denver, Colorado, where she worked as a laundress, and then in permanent employment as housekeeper for Mrs. Juliet Coney, a widowed schoolteacher from Boston, Massachusetts.
In early 1909, Henry Clyde Stewart (1868–1948), a widower, placed an advertisement in The Denver Post for a housekeeper to help on his homestead near Burntfork, Wyoming. Elinore answered it (with the agreement of Mrs. Coney), and was accepted. She arrived there in March 1909; in early May, she filed a claim for a quarter section adjoining Clyde's homestead under one of the Homestead Acts; and on May 5, she and Clyde were married. Around this time, she began to correspond with Mrs. Coney, in a series of letters which continued until 1914. Those letters were published in Atlantic Monthly and later collected in the books Letters of a Woman Homesteader (1914) and Letters on an Elk Hunt (1915).