Linsey-woolsey is a type of cloth made out of, as the name hints, flax which is linen and wool.
This fabric is pretty old. It was worn by the pioneers in North America, but it dates back to the Old Testament times. It is mentioned in Leviticus 19:19 and Deuteronomy 22:11. Oddly, in both references God is forbidding the Jews from wearing this garment. A Jewish blog gave several reasons why this may not be allowed and this answer was pretty interesting.
“The Midrash suggests that the reason stems from the story of Cain and Abel, as recorded in Genesis chapter 4. Cain brought God an offering of flax (the source of linen) and Abel brought a sheep (wool). The incident resulted in Cain killing Abel, and it was thus decreed that never again shall the two substances mix.” (quoted from aish.com)
This fabric was used by the pioneers because the wool was scarce, so they mixed it with flax. Although it is no longer a common fabric, it still is continuing to be made in small quantities for historical recreation and Colonial period decorating uses.
Useless info: STUFF is a term originally used to mean machine-made fabric.