10-year-old Kayla Ridley and 9-year-old Bryce Johnson spotted Stewart in one of his normal spots.
"Thought it was awesome," Johnson says.
"He was representing our country by waving American flags," Ridley says.
Stewart's dedication inspired the youngsters.
"We decided that we wanted to make money for him," Ridley says.
On their spring break, they spent two days running a lemonade stand.
They brought in more than $60. Then, they took a trip back to the riverfront to deliver the donation to Stewart.
"We felt great on what's he doing, representing our country in a good way," Johnson says.
"That's really saying something - that people really appreciate what you're doing," Stewart says.
Stewart plans to use some of the money to help pay for bills, but a lot of the cash will go towards new flags.
Until he gets a chance to add to his growing collection, Stewart says he's humbled by what Ridley and Johnson did.
He says it's only more motivation to keep up his all-time favorite hobby.
"There's good people in this world, good people, good people," Stewart says. "I know that."
After seeing how successful the first lemonade stand was, Ridley and Johnson say they plan to do another one in the coming months.
The money they raise will once again go to Stewart, a man who makes hundreds smile nearly every day.
Copyright 2016 WFIE. All rights reserved.