Since the blue fabric was so heavy, I stitched around the seam, to hold down the seam allowances. It wasn't necessary but I think it looks nice.
The cushion cover is not a flat front and a flat back, but rather has a gusset all around it, giving it "depth". I rather like that look.
There's still more fabric left... I don't know if my sister-in-law would like another identical pillow, or something more creative instead. Any ideas?