Pillow Case or Quilt Block?

I made this block last night, thinking it would become a pillow case, but it turned out one inch smaller than I had intended - 23" instead of 24". I haven't confirmed it yet but I believe I'm sewing a larger seam allowance than 1/4". It's hard to tell on my machine so I will fiddle with it tonight and actually measure the space. Pretty great for a beginning sewer! My favorite piece is the center square which is a Marimekko fabric. It's got a most wonderful texture that's just a little bit rough like linen or canvas. The two flowers in the upper and bottom corners are Kaffe Fassett fabric. I love just about everything I see from Kaffe Fassett. I'll definitely be working with more of those fabrics soon. I've picked up a few Brandon Mably fabrics that I love so will be using them soon. But as far as this block goes, I'm starting to consider it the beginning of a new quilt. Mind you, I've already got one ambitious quilt project in the works that will take a while (I'll begin posting my progress soon). But I would really love to see nine blocks of a variation of this design and these fabrics.