John gives Sherlock the skull, kidfic

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So I read a fic a while back about how when John was growing up he always knew what people needed. He would just know to take an extra sock with him because someone at some point would need it that day. He is the one who gives Sherlock the skull (I think Sherlock is in a sandbox at the time).
I have been looking for this fic for a while and cannot find it again. Any help would be greatly appreciated.

FOUND: link in comments, thank you so much midori_marmotte!