Bakery girl, rude woman at work, I believe shadow curios person?
Yeah unfortunately, you have to give them to those people or else you can't unlock certain aspects of the game. Baker girl gives you an ingredient for the sandwich. Curios unlocks the sandwich. Hyper girl, I don't think unlocks anything specific and I think, after a certain point, you can't give it to her since you can't access the Glizzard competitions if you get too big - they just stop happening.