I work for a local hotel and have grabbed stained sheets & pillow cases to use for projects. I have "home-dyed" them and have an unlimited variety of colors! A standard pillow case is about 30"x 30" once seams are cut off and hem removed. Most of the ones I use are at least 50-50 cotton/poly. If nothing else they are soft and easy to work with! Most hotels/motels are more than willing to give away their discards, saves having to pay to have them put in garbage! What stains there are can easily be cut around for piecing. I also agree with going to Wally's for backing material (king sheets)!