I saw a vid on here a few days ago, the thread was called 'save your stems' if you wanna look it up.
Anyway, this guy saved up a load of stem (just over an eighth of stem), put it in a pollinator and got loads of kief from it. I suppose you could save them up and cook with them, but youd wanna put some bud in aswell. Just look up 'cannabutter' on Google.