About a year later, on vacation in Florida, he saw a TV news report about the anniversary of the march. And there he was.
"I told everyone 'I saw myself on TV.' They said, 'Sure, you're dreaming,'" Collins said.
One of his daughters, a teacher, has used his story to teach students about the civil rights movement.
Collins' nephew, Kenny Shugars, a retired deputy U.S. marshal, shows the March on Washington picture to his criminal justice students at Georgia Regents University at the start of each semester.
Shugars and Collins always traded cop stories over the years, but it wasn't until about five years ago that Shugars learned of his uncle's brush with history when the picture was shown on TV.
"He's not one of these guys who goes out and brags. He's very humble," Shugars said.
With the 50th anniversary of the march approaching, Collins suddenly finds himself in demand for his minor role in history. It began while he was surfing a website for retired officers from the Metropolitan Police Department. There was a request from Howard University seeking to get in touch with police officers who worked that day. That led to interviews with researchers from Howard.
Then Collins read about the Foot Soldiers Memorial, to be dedicated Wednesday in Annapolis, honoring the "regular people" who participated in the March on Washington. Collins contacted organizers of the memorial, who have shared his story with anyone who would listen.
In recent weeks, he's been interviewed more times than he can remember — an odd experience for a man who has led a quiet life as a police officer, parking enforcement communications officer and court reporter. He's had two marriages, eight children and stepchildren, and nine grandchildren.
"I'm flabbergasted," Collins said. "I never thought it would lead to anything like this."
But Carl Snowden, the driving force behind the Annapolis memorial, said it's appropriate to honor regular people such as Collins who played a role in history.
"He had a view of history and didn't even know it," Snowden said. "I'm sure Kenneth Collins had no idea that the black Baptist preacher he was listening to would one day be an international icon."
Snowden hopes people will be inspired by the stories of Collins and others who attended the march. He has invited dozens to Wednesday's memorial unveiling in Annapolis.
"We want to use this occasion to say thank you to them while they're still living, that we're appreciative of the sacrifices they made," he said.