$1 sweater at local thrift shop (half price day. love that.), 100% cotton.....
I may be the last knitter on the block to try recycling yarn like this, and I'm not quite sure what took me so long. Perhaps I knew I'd get that crazy thrifty rush I get from turning something old into something new, and that my yarn stash would never again be contained. Nonetheless, I tried it. And it was SO MUCH FUN. No really, it made me very very happy. I don't even have a plan for this yarn, I just love that this is possible. That something new can come of something that was to be 'discarded'. On so many levels, that is very very cool.
I never understood how to do this when my grandmother would tell me about how she did it as a child (when, of course, this wasn't just a thrill, but a necessity), but I totally got 'how' to do it when I found this fabulous tutorial.