That event should be the little boy. There should be another event, the shelf, that, when pressed action button, does this:
>>EVENT PAGE 1: ACTION BUTTON
@>Show message: Wow! That shelf is high. *huff* *puff* (Or something like that)
@>Show message: Yay, I've got it!
@>Play ME: Fanfare1 (Or whatever you feel like. You could even do no ME)
@>Increase item: Stone +1
@>Self switch A: ON
@>
>>EVENT PAGE 1: ACTION BUTTON - Self switch A == on
@>
Don't forget to make sure the player can't drop/use/sell the stone!