A solid wool petticoat is a warm and useful addition to any lady's wardrobe. Wool petticoats of the mid-nineteenth-century were generally made of cotton for the first six inches, presumably to reduce bulk at the waist (can you imagine gathering 120"+ of thick, heavy wool into a waistband?!).
I found my wool at Goodwill--it was a long, extra-wide, solid strip with a slit 2/3 of the way through the middle. I can't imagine what someone was using it for. But it worked for me--I continued the slit and sewed the two strips together to make a very long piece of wool, which was then sewn to the 6" piece of cotton, which was then gathered to a waistband and finished nicely with an ivory button. :)
Generally they were worn as an innermost layer, under the majority of the petticoats, but mine is so large I wear it on top of all my petticoats, and it acts almost like a cage crinoline! Very heavy of course, but very warm, and one quickly gets used to the weight. I agonized for ages on what to make from this wool; it's rather coarse and isn't dress weight so it wouldn't really be suitable for anything but undergarments (which, hopefully, no one will see!) or blankets...and I already have a wool blanket. ;) So finally, the evening before a rather chilly reenactment, I had inspiration and was able to whip this up!
You can read more about the construction of wool petticoats here.