I've made these flat Ceramic Easter Egg plaques. They are glossy on the front and left plain on the back so with a texta you could write a message on the back to mark such a precious occasion - name, date etc. It would be something that could be hung on their wall and be something very special to keep for years.
Could be a great idea for an interstate Grandparent who wants send something to their first grandchild, perhaps?!?
They would also make great and unique Gift Tags.