My first thought on seeing your pillow was did you clip into the corners...this releases tension on the fabric and allows you turn corners and have a nice flat appearance. Perhaps someone else has another idea...this is when I wish we could all live "across the fence" ...so much easier to help fix in person. As for the closing.....where is the closing...outter edge or around the red square? It might sound silly but i've seen them everywhere. Usually a very small overcast works...or even stitching very close to the edge with a machine. Budster

I had considered clipping the corners to release the tension. I will do that and see if it helps. The closing will be on the edge, and my closings always look terrible. I'm going to aplique a green tree silhouette in the red square. I don't know about doing the edge on the machine, it might look "pressed". I could use fabric glue, but I would like to sew instead of cheat. Thanks for the advice!

I was also going to say clip the corners,that should make it lay flat.I always make my pillows with a fold over opening on the back,so that the pillow form can be slipped in and out easily for washing of the cover,or changing of the seasons.
Kathi