m.kitchengirl, neat idea for the big floor pillows. I think it was Elizabeth Zimmerman who wrote directions for the Pi Blanket, a flat round knitted blanket. (there are examples on Ravelry) That pattern has the increases for knitting a flat circle. To make a pillow it would be a matter of not increasing stitches when wide enough to make the side walls, then reversing the pattern to knit back to the center. In theory.
I know this is a knitting thread but I have crocheted a number of large cat beds, 2 strands, 20'' in diameter, the sides are about 20'' and are folded back to make a 10'' double thick side wall. The pattern could easily be made into a pillow. They are very fast to make, if this is of interest I can write up directions. Sorry to hijack the thread with crochet!