Foster said her lifelong passion for public performance began when she was seven years old. A talented pianist, she performed at society functions as "Little Miss Foster", and gave a recital at the White House during the administration of President Rutherford B. Hayes. After graduating from high school, her hopes of studying music in Europe were dashed when her father refused permission, and funding. In 1885, at the age of 17, Florence eloped with Frank Thornton Jenkins, a physician 16 years her senior, to Philadelphia, where they married. The following year, after learning that she had contracted syphilis from her husband, she ended their relationship and reportedly never spoke of him again. Years later, she claimed to have been granted a divorce decree on March 24, 1902, although no documentation of any such ruling has been found. She retained the Jenkins surname for the remainder of her life.