This pic is of the fluff that comes out of the pods of Asclepias syriaca. There's a lot of it this time of year and its really interesting to read about the uses to which it has been put over the centuries.
The fluff can be spun into beautiful yarn, but it is not strong, so this spinner recommends blending it with something else.
The insulating properties of milkweed fluff are well known and have been taken advantage of for centuries. Here's a site that tells you exactly how to collect it in quantities that you can use for making clothing, etc.