This prompt comes from the amazing poet Phillip B. Williams (@PBW_Poet on Twitter and check out his website with links to his published poems, including “Bend as Would a God”):
What is something that you wish your younger self would teach you if they could travel into the future to visit you? What have you forgotten, misplaced, or destroyed of your younger self that you see, now, would be a blessing to have?

I also posted his Tweet on Facebook: https://www.facebook.com/1422811947/posts/10217473651779527/

This is off topic somewhat (and I think I have already linked this poem since I love it so much), but check out “One Art” Elizabeth Bishop. Here is another take on the prompt: the poem “Lost and Found” by Maxine Chernoff. And another: “Childhood Ideogram” by Larry Levis.