Sessions was born in San Francisco, California, and educated in Oakland.[1] At the age of six, she moved with her family to a farm next to Lake Merritt.[2] She attended the University of California, Berkeley in 1881 with a degree in natural science.[2] While attending a San Francisco business school, at the request of a friend, she moved to San Diego in 1883 to work as an eighth grade teacher and vice principal at Russ School (now San Diego High School).[2][3] She worked at the school for over a year before she left due to health problems.[2]