I save a lot of the above, but two other things that come to mind are:
I'm a scrapbooker, too. Many of the items (papers, page protectors, etc) come reinforced with a heavy piece of cardboard. I keep the cardboard to wrap fabric around. I also make "bolts" of bindings ready to sew. They are all cut and pressed in half.
I keep the little plastic zippered pouches that things in the linen dept. come packaged in. Pillow cases come to mind. Those little pouches are the right size for cut pieces, scraps of a certain color or size, etc. I also use them with my scrapbooking supplies. Nice to assemble smaller items. And you can see what's in them.