Yes, I've seen pillows (and even made some) that had crochet stitches worked on top of crocheted fabric. Basically, you work the stitches with the crochet hook on top and the working yarn underneath, and you're pulling the yarn up to form your stitches.
These from Crochet! Magazine
are worked in this way: http://www.ravelry.com/patterns/libr...l-pillows-mali