Hand dyed colours and undyed.
If you aren't familiar with Thrum Mitts I found this on Knitting Daily
I had a pair of thrum mitts. Unfortunately I have no clue where they are. I loved them. When the Grey Cup was in Hamilton I wore my mitts to the game. My hands were very warm. The rest of me froze but my hands were happy."Thrum" originally referred to the short lengths of waste yarn leftover after woven cloth was cut off the loom. In the spirit of necessary thriftiness, craftspeople would find a variety of uses for these thrums--stuffing pillows and mattresses, and after a while, knitting them into mittens and hats to provide an extra layer of warmth.Each thrum, or short length of yarn, would be worked together with the main knitting yarn as a single stitch, with the ends of the thrum left hanging inside the mitten to provide insulation. Lovely! Except that people soon discovered that the yarny thrums could catch on fingers, and even fray.The second type of thrum works much better, and has been a tradition for generations in the chilly-but-gorgeous environs of Newfoundland and Labrador up here in Canada. This type of thrum is actually roving, or unspun sheep's wool, separated into wisps, which are then knit into the stitches along with the working yarn as before. The ends of the fleece form little poufy pillows inside your mittens, and your fingers start thanking you the minute a pair of thrummed mittens is on your hands.Basically, you're making a sheepskin for the inside of your mittens. With the wide variety of dyed wool roving available these days, you can choose a rainbow of colors from which to make your thrums. (You can purchase unspun roving at many local yarn shops; or take a trip to your local fibre festival!)
Here is a great tutorial from The Yarn Harlot for making thrum mitts...
The day started out slow in the store and I thought that there was going to be lots of knitting accomplished this afternoon. The store got crazy. A customer had a mistake in a scarf and I took out 600 stitches for her. Then I fixed the neck on someone else's sweater. There were lots of people buying yarn and Christmas gifts. I'm not complaining. I love a busy store. It means no pictures of my knitting tonight. The shawl hasn't grown. I've been working on other chores tonight like writing cheques and cleaning the kitchen. Now it's time to watch the football and knit. Go Dez Bryant! We need him to get lots of yards to win our fantasy football match this week. We're in the playoffs now. Lose and we're done.