Mary Myrtle Siler was born June 20, 1887 in the Matthews Township of Siler City to Elizabeth Matthews and Rezin Cicero Siler. Siler City is named after Mary Myrtle Siler’s grandfather, Samuel Siler. Previously, Siler City was named Matthews Crossroads after Mary Myrtle Siler’s mother’s family. 

     Siler’s childhood was a sad one with all of her seven siblings passing away before her 24th birthday. Siler’s mother also passed away when Siler was around 15 years old.

     Siler attended the Siler City Institute for primary school. For additional schooling, she attended State Normal at Greensboro, today known as the University of North Carolina at Greensboro.

     After her schooling, Siler returned home to become her father’s caretaker. Upon her father’s death in 1911, Siler moved to Pittsboro to work as a clerk in the sheriff's department.

    During her 10 year run as clerk, Siler’s life is well documented due to her lineage in one of Chatham County’s oldest families. Her social life is documented in newspapers of the time. She is recorded as being an active church member and volunteer with the local Red Cross during World War I. She was also an advocate for women’s rights and a non-drinking state, pre-prohibition.

     When Leon T. Lane, Siler's cousin, resigned from his position as Sheriff in order to run for another position in government, Mary Myrtle Siler was approved unanimously by the county's all-male Board of Commissioners to fill his position. She was sworn in as sheriff on October 4, 1920.

     As sheriff, Siler was responsible for 13 part-time deputies, who represented each of Chatham County’s townships. Work of the time would have mostly consisted of serving warrants and reporting suspected illegal activities. 

     Siler’s time as sheriff is memorable not only at the county level. Along with being the first female sheriff in Chatham County, Siler’s term marked the term of the first female sheriff in the state of North Carolina. She also is remembered as one of the earliest female sheriffs across the nation.

     On December 22, 1920, Siler and William Reid Thompson married at Pittsboro Baptist Church. He was from the Baldwin Township of Chatham County and  had recently been appointed as superintendent of schools. Siler was 33 years old at the time, older for marriage during that period. Siler family lore says that Siler did not include a pledge to obey her husband in her vows. This would have been a reflection of her dedication to the advancement of women’s rights and supposed concern that her husband may do something God would not approve of. After her marriage, Siler left the sheriff's department. 

     Siler then went to work as a clerk in her husband’s office. The couple also purchased land on Hillsboro Street adjacent to the historic Wade Barber House. 

     In 1939, her husband died and Siler opened her home to local school teachers as borders.

     She died March 30, 1985 at 97 years old. She is buried at Love’s Creek Baptist Church in Siler City.