The picture of the sandbox at the grave went viral on Facebook with more than 220,000 users sharing the photo.
Ashlee Hammac, 24, says she originally planned to decorate the gravesite of her son Ryan with glass pebbles. Then she realized her 3-year old son, Tucker, needed his own place to mourn.
Hammac told People, "The more I thought about it, the more I wanted something my other son Tucker could be incorporated in. He always goes out there with me, and sits out there, and sings lullabies, and talks to him just like he was there. So I wanted it to be special for him too."
Tucker often asks his mother if he can go to "baby Ryan's sandbox." Hammac sees this as a way for Ryan to be a part of their family.
Baby Ryan died five days after he was born in Oct. 2013 because of Hypoxic-Ischemic Encephlopathy, or HIE, a brain dysfunction that occurs when there is a lack of blood flow to the brain.
While Hammac was overcome with grief, she says she was comforted by the fact that Ryan was able to give back in death. Ryan's healthy heart was donated to save the life of another baby. Hammac says she hopes to meet the other mother and baby someday.