Just cut your baggie down both sides so its one sheet and take a credit card and scrap down it. Been through a literal thousand bags of many many different substances and this works the best.
edit: It may be hard, but do not try and get every tiny morsel out. Just aim for getting the most out, as if youve got a few bags you could get a dose, but the tiny bit your leaving behind isnt enough to fret over (ok, it might be enough to fret over, but thats cuz your tweaked out scrapping bags lmao). then throw the bags away. trust me on that lol.