Mary Mildred Williams was a light-skinned Black child born into slavery who became identified in the popular imagination with "Ida May," the fictional kidnapped white child in Mary Hayden Pike’s novel, Ida May: A Story of Things Actual and Possible. Williams was freed at age 7 through the efforts of her father, a freedom seeker, and influential men in Massachusetts including Charles Sumner.

Mary and Oscar’s father Seth Botts changed his name to Henry Williams when he arrived in Boston. He and his family are listed in the 1855 census of Boston under the Williams surname.

A note enclosed with the daguerreotype reads, "Slave child in which Gov. Andrew was interested."