Good ol silkworms!
They come in Normal, Zebra, and reverse zebra. And then theres the not so much a morph morphs, they look like normal silkworms but they spin different colored cocoons. Like Green, pink, and gold. Im guessing the colored ones are how they get certain colored silks. they sell the eggs here, Ive gotten the Zebra silks before, and a few gold spinners.
http://www.mulberryfarms.com/store/i...dex&cPath=1_43