If I were going to use poly fabrics I would also use poly for the batting. You shouldn't have to worry about shrinking that way.

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.

Welcome to one of most opinionated hobbies in existence! Ask 15 quilters ... you'll get 15 different answers none of which are 'wrong'.

To add to Mariposa's idea, you could also make some dinomite pillowcases!

For what it's worth, I was taught that you don't mix poly fibers with cotton for all the reasons listed above but also because poly is stronger than cotton. The theory presented to me in this class was that the stronger fabric would 'wear out' the natural fiber. I was taught use cotton thread and not to use poly thread on cotton for the same reason.

Bottom line, use caution, and don't make an 'heirloom' using mixed fibers.

You're in for a wild ride ... quilting is a 'calling'!

Peggy in Frigid Florida

its'll be fine just try to keep the blend with the blends due to shrinking and fading.. .. Ive made all blends quilts, and they turn out fine..

Use them. Wash them first.

For all the reasons listed above, I am constantly amazed that we think cotton is the "only" fiber to use in quilts. Poly doesn't shrink, it doesn't fade (especially the black), it is more durable and dries faster. Personally I like the sheen of poly and have no problem using it. I can understand not mixing the 2 fabrics with the sheen of the poly and the dull appearance to cottons. So then, too, why do we like poly battings with cotton tops?
Now that cotton prices are going up, it will be interesting to see if we come around to thinking poly is just the most wonderful fabric again. My mother made a lot of her quilts with polyesters and they are standing the test of time quite nicely--all hand quilted.

There is a perfect project for every fabric and the perfect way to make it happen. Don't throw it away. You may need it later.

I agree to just use the fabric you have. I would just not mix blend fabric with all cotton. But I have made a lot of throw size quilts that I gave as gifts and no one has never accepted a quilt because it is not all cotton fabric.
I personally believe that not all quilters use expensive cottons, use what you can afford and enjoy just making quilts. That is what I do.
Pickle

I once seen a picture of a Lone Star quilt made out of denim and velvet or velveteen. It turned out really fantastic! I don't know how well it wore or anything like that but I would say use it.

I will still occasionally use a blend as there are times you just cannot get the color you want in cotton. Use the pieces you have, sometimes the blends are harder to work with. applique can be very frustrating with blends, but for piecing, just use them. the quilt police will not come take you away!! grin