Wool. I didn't know any better, I thought it *HAD* to be wool.
One was this oversized Puruvian stained sweater (I don't know what I was thinking) made from thick one ply wool replete with burrs!. Most of it was undyed wool. It's just balled up. I need to wash it. I don't know what I'll do with it.
The other was a two ply thin, really easy to break wool from a Scottish sweater. It had a lovely grey yarn, and vibrant reds, blacks, some white. I used it for my first projects, toy balls, which I felted to hide my mistakes!! I still have some of the grey.
[Edited to add] I couldn't have paid more than $2 USD for each one.