The Button Box.
I have this thing where I can't throw away nice packages/bags/boxes. It's bad enough when nice wrapping paper has to go in the trash, because no matter how carefully you try to unwrap it, a rip comes & ruins everything.
Whenever I open a beautifully wrapped gift, I feel this slight uneasiness about undoing someone's thoughtful labor.
It makes sense to also have a needle & thread inside, but mine are currently on a shelf in the linen closet.
Though I can't remember having to actually pick a button from this box & sew it on, it feels nice to have them on-hand.