She was born on December 10, 1906, in Washington, D.C.[2] Her siblings were brother, Perry, who died of an injury while attending Virginia Tech, and Lydia, a history teacher at Stratford College.

Mary's father relocated the family to the mill town of Danville, Virginia located in Pittsylvania County.

While still a young child, she discovered that many of the local school children in Schoolfield, Virginia, which is a suburb of Danville, did not have access to books.

To help alleviate this situation, she convinced her mother to help collect money to start a school library in this nearby town.

This unplanned job transfer, led to a long career as a librarian and advocate for the development of school libraries.

[8] She also embarked on an international mission to assist other countries improve their library systems, worked as a visiting professor at the University of Teheran, and became an advisor to Iran in 1952–1953.

She was passionate about her work and wanted others to realize the importance of a well trained library staff and the benefit it had on the students' educational outcomes.

These awards include: Gaver's career and influence as a librarian and author did not end when she retired from Rutgers University.

She continued to conduct research, write, edit and publish articles well after her career as an educator ended.