[TOMT][Kids/Scholastic? book] Bag of bones

This was a book I had received from those Scholastic book orders in grade school (prob 30 years ago). It was possibly a Halloween themed book about a young boy who has this bag of bones he drags around. He has an encounter with a witch (who maybe tried to eat him) and other creatures, he finds himself in a house with no doors or windows. At the end the bones turn into a skeleton, I think. This book used to freak the hell out of me when I was younger!