I LOVE making throw pillows from placemats. Half of the work is done for you. I made this week's throw pillow from two IKEA MARIT Placemats. They cost me about a dollar each and measure 14" by 18". I used IKEA's 16" by 20" pillow form, which runs $2.99. It's the same kind of pillow form that I used for this pillow a few weeks back. These placemats are only one piece of fabric and don't have a ready-made pillow back like some that I use (and added a few extra steps to my pillow-making process).
To make my pillowcase, I lined my two placemats up on top of each other and sewed a white zipper down one side. As always, I sewed a zipper into this pillow case to make for easy cover removal and cleaning down the line. I then sewed the remaining three sides closed. Usually, I would do this by lining my two placemats up with their right sides together (meaning that the pretty fabric that will eventually show is inside and what will ultimately live inside of the pillow is facing out). But, these placemats kind of have a woven, rustic, scalloped edge on the two long sides that I really liked and didn't want to lose. You can kind of see it along the top here:
In order to keep that little edge in tact, I lined the placemats up (after inserting the zipper) with their right sides facing out. I pinned all along the edge of the placemats and used a straight stitch and sewed along the long sides as close to the edge as I could. My pillow is actually different colors on each side (one blue placemat and one white placemat), so I loaded my sewing machine's bobbin with blue thread and the top part of the machine with white thread and sewed with the white side facing up.
I hand sewed the final side using a slip stitch and blue thread. The stitching is blends into the fabric in the completed pillow. The only reason that I sewed it by hand was because I could do it on the train and I knew that it would be a little bit more hidden than if I sewed it by machine.
And here is the front and back of my completed pillow: