This is how I made the scrappy rag rug featured over at Homeliving
If you know how to crochet, you can make a rug like this. All you need is a 'Q' sized hook (the biggest you can find) and a really strong arm!
I do not have any step-by-step instructions for how many stitches to take, but any basic flat crochet work instructions will do, such as a placemat, for instance. A pattern will give you the number of increases to take for rectangular, round or oval shapes so things do not get out of whack and look funny. Something simple with single crochet is good. I also found some helpful tips on the web at this site.
I cut up old cotton skirts and fabric scraps, and it is best to cut on the grain-line. Strips that will fold to 1/2 to 1 inch will be easier, but if you want something really thick( and difficult to crochet!), cut the strips wide and fold them to 2 inches.
Sew the strips together (flat) at the ends, and roll into a ball, or sew as you go. You can iron all the edges folded in (similar to making bias tape) or you can sort of fold them in with your fingers as you go. You will end up with some frayed edges if you choose the last method, but if you like a real old-scrappy-this has been here for a while-look, it should be fine.
Crochet loosely and it will work better for you, and be easier on your arm.
I experimented with making fleece rugs a couple of years ago. Fleece is so wonderful for crocheting rugs because it just slides right through the stitches, and you do not have to do anything about the raw edges. It makes a really nice warm soft rug. Cut on the 'grain' with fleece! I had cut strips of bias for one rug and it really made the rug stretchy!
I found that sometimes fleece blankets on sale are less expensive than yardage, though there are some good fleece sales to be had at the fabric stores.
There are more beautiful cotton crocheted rugs to be seen, it was quite a popular hobby in the mid-1990's where I used to live. I remember seeing heart-shaped rugs with scalloped borders of contrasting colors, done in polished cotton big floral prints and solids to match the decor of the home.