From About Women’s History:
She claimed May 1, 1830 as her birthday, but she was really likely born on August 1, 1837.
Mother [Mary Harris] Jones, the white-haired radical labor organizer known especially for her support of United Mine Workers strikes, was well aware of the impact her image had and carefully nurtured that image.
While she may have exaggerated her age, she was much beloved within the ranks of labor for her ardent and reliable support. Read more: here.