The tutorial I first found included cutting and sewing the pillowcase. I hate sewing and will find any way I can to avoid it. It's not that I hate sewing actually, I am just really terrible at it and do not really have the patience.
So...why not just cut the pillowcase and tie it? They will make handy and responsible shopping bags. I just throw them in my purse so I always have one on hand at the store.
No Sew Pillowcase Bag
2. Decide how deep you want the bag to be or how wide an arm hole you would like. Then cut.
3. Tie the two ends together and pull tight in both directions to make sure that the knot is secure.
I have tested them several times with my groceries and so far, so good! Now I always have a bag on-hand!