I don't think you can go wrong with old army blankets. They have been washed more than once and boy, are they warm. With 3 brothers in the Navy, we had a good assortment of blankets which my frugal mother used to make quilts.
They were tied also and were heavy also. I remember that it was difficult to turn over under such a quilt but I also remember how warm they were. (in my 80's now, so that was a long time ago.