Why a pillow case? Well, it was originally Trish's idea so she would know for sure. It started a few years ago when we picked way more blueberries than we could reasonably store in ziplock bags, so Trish put them in a pillow case and that worked perfectly. Anytime we wanted blueberries, we just opened it, scooped out the berries we wanted, and then tied it back closed. Since then we put all our big frozen items in pillowcases if there is more than, say, 3 gallons worth.
We use ziplock bags for the smaller things, like fresh shelled southern peas. Those go in quart bags. Peeled and sliced cantaloupes go in gallon ziplock bags.
They are definitely very mushy when thawed but that's okay since we only do this for our saucing tomatoes.