My first quilt was a stack and whack with one cotton and one poly/cotton blend. The one thing I noticed is that the poly stretches a lot more than the cotton. You can do it just be careful. I had a woman bring me fabric for a trip around the world, and you wouldn't believe the fabric. There were 100% cottons, 100% flannels, a poly/cotton blend, and there was some kind of a poly or rayon that frayed like you wouldn't believe. I ended up serging it and it took forever. I couldn't believe with such an odd combination of colors and fabrics, it turned out quite well.