Born in Cincinnati, Ohio, Nellie was the fourth of eleven children of Judge John Williamson Herron (1827–1912), a college classmate with Benjamin Harrison and a law partner of Rutherford B. Hayes. Her mother, Harriet Collins Herron (1833–1902), was the daughter and the sister of U.S. congressmen; Nellie's grandfather, Ela Collins, and uncle, william Collins, were both members of Congress. During her childhood she was called Nelli rather than Helen; she was referred to as such in the family since her only daughter was named Helene. Nellie Herron was enrolled in private Miss Nourse School, known in Cincinnati as The Nursery, in 1866-1879, and took classes from the University of Cincinnati. Starting from 1882, she taught in different schools until her marriage. In 1877, she attended with her parents the twenty-fifth wedding anniversary celebration of President and Mrs. Rutherford B. Hayes and stayed for a week at the White House.