Her son, Max Barry, died from an apparent overdose
on July 29, the mayor and her husband, Bruce, said in a statement
The mayor began her first day back at work by greeting children who were on their first day back to school, according to CNN affiliate WKRN.
She handed out supplies and backpacks to the young students.
Barry told reporters that the first day of school was always "meaningful and special to me."
"The first day of school in our household was always a joyous occasion. Max loved school and our ritual was that we would always take a picture every day of the first day of school," she said.
"I was really happy that he continued that tradition for me when he went to college. Freshman year, sophomore year, junior year and senior year, he would take a picture and send it back to me."
She spoke, often emotionally and with tears welling in her eyes, about how she was coping with her son's death.
"The new normal for me is, I get to get up every day now and I don't get to ever talk to my son again. Max, as most kids his age, was a regular texter. The normal is Max is not going to text me back," she said. "The work of our city goes on. Every day I'll get up and do what needs to be done."
Max Barry died in the Littleton area, a suburb of Denver, the Jefferson County, Colorado, Sheriff's Office told CNN last month.
He had gone to rehab last summer, his mother said.
She said she didn't know what drugs caused his death, in comments carried by WKRN.
After his death, Barry and her husband decided that they would be open about how Max had died.
"My hope is that it will inspire other parents out there to have frank conversations with their own children and if that saves one life, that's a blessing," she said.