When a child, a young boy, is looking through a chest, he probably is not knowing what he will find.
The significance of the boy finding his own drawings is that, to someone else besides him, the drawings were very important and represented something that truly mattered.
This find places a new light on his search because he now understands that his drawings have or had meaning to someone and that there is a mystery to the meaning.
This finding may present a challenge to him that he can explore and find out why they were saved, by whom and what their specific significance is to his life or to the lives of others.