I have been wanting to make a straw mattress for a long time now. I read testaments of straw beds being the most comfortable and warm beds one could ever sleep on in the Foxfire Book Series. I visited Thoreau's cabin--or replicated cabin--and studied the anti-decor of his three legged-desk, fire wood box, and straw-filled-mattress bed. I realized that before toxic synthetic non-biodegradable polyfoams, metal coils, and plywood, people made their own beds out of simple and abundant natural materials.
So now my son, almost five, is ready for his own bed. Natural mattresses made from wool and organic cotton, or natural latex are only affordable to inhabitants of the Upper Middle-Class. Straw it is, then. And why not? I have been warned by the hillbilly accounts in Foxfire to change out the old straw for new every six months to prevent bed bugs. So for the reasonable price of $2 for a local straw bale twice a year, I can keep the bed bugs from biting, and the straw smells so sweet and earthy.
To make the mattress I bought 4 yards (for an adult bed you would want 5 or 6 yards) of 100% cotton duck cloth (a canvas-like material). I then essentially sewed a pouch with a drawstring and inner flap at one end to hold in the straw and to make it easy to replace with fresh straw when the time comes. You could also sew in a zipper, which would keep the bed square shaped instead of rounded at the end like mine, but I didn't want any metal. I then stuffed the pouch with one dry straw bale, cinched her up a bit and carried her to the bedroom. Now I have one happy boy whose bed won't outlive him by eons. And the whole thing cost a total of $32. They sure knew how to do things right pre-industrial revolution!
http://en.wikipedia.org/wiki/Foxfire_(magazine)
http://www.oldandinteresting.com/straw-mattresses.aspx