You can make a pillow out of just about any type of fabric, it all just depends on what the pillow is being used for (sleeping or decorative). If its for personal use to sleep on i would stick with a cotton or linen type of fabric for comfort. If its decorative you can be creative and the possibilities are endless, old clothing, leather, bandanas, furry, etc. If your having any doubts you could always just ask the person working in the fabric department what your best choices would be.
Go to a fabric store and feel all the fabrics for yourself. You can tell by intuition. Just know the tougher the fabric is, the harder it'll be to sew. So go for something kind of in between. You can also check the tag on one of your store-factory-made pillow cases. Maybe that'll help.