Story highlights Carson Cheney was killed just weeks before his 5th birthday when a headstone fell on him

Boy's family decided to co-opt the toy cars Carson loved for pay-it-forward remembrance

Cars have been found across nation and in Japan, Germany, Sweden, Italy and beyond

(CNN) Hilary and Zac Cheney are delighted that people have found connections to their late 4-year-old son across the nation. Those ties have even transcended international borders.

The toy car that Carson was holding when a 100-year-old gravestone fell on him, ending his brief life in 2012, has sparked a pay-it-forward movement to remember the boy's courage.

Where some families might see the tiny 1970 Chevrolet Camaro as a bitter reminder of their loss, the Cheneys keep it as a warm memento. It comforts them.

"They delivered it to me an hour later and I carried that car around with me for weeks," Hilary Cheney said. "I even slept with it under my pillow. Knowing it was the last thing Carson had played with makes it one of my most valued treasures."

That blue-and-white-striped Hot Wheels car sits in a glass case in their family room, she said.

Read More