Easiest way to get Coarse, Rough and Tacky Silks it to make a new toon and go into tutorial. There are usually hundreds of them to purchase on venders there.
Lots of this, coarse silk, rough silk and sullied silk in the Gloomingdeep tutorial too. My new character has stacks of the stuff, but vendors won't buy it and the planar sewing kit won't do anything with them, saying "You cannot combine these items in this container type"