Carson Cheney was killed when a 100-year-old headstone toppled over on top of him, KUTV reported. The family was at the Utah cemetery visiting the graves of family.

>> Read more trending stories  

The 4-year-old's mother told the station her son always had a small car in his hand.

"He was holding a Hot Wheels car when he passed away," Hilary Cheney told KUTV. "I felt strongly that we needed to continue to share Carson's light with these toys."

At first, Carson's Courage Cars were found all over the United States, then the movement spread across the world, with cars being found in Germany, Brazil and Mongolia.

Each car that is hidden has a tag that reads "Finders Keepers. Please Enjoy this Gift in Honor of Carson Cheney."

Finders are encouraged to post the photo of the car and where it was found.

More than 15,000 cars have been hidden across the world, KUTV reported.