So here is the thing. I have been mixing line drawing and Photoshop texture for some time, but I never once made my own brushes. This is tantamount to someone who enjoys pasta but never makes their own sauce. Why wouldn't you just open up a can of Muir Glen diced tomaters and fry up some garlic? It's hardly difficult and life will improve by 12% (actual statistic that I made up).
To make the brushes I scanned an assortment of textures. I used crayon, graphite, and an ink brush.
Then I followed this tutorial from Smashing Magazine to make brushes for the background of this icon illustration.
The story behind the project is that a tiny adorable person of my acquaintance is feeling a little nervous around dogs. His folks have been assuring him that St. Michael will protect him from doggies with an angelic disapproving finger wag. They required a "Bad Dog No Biscuit" icon for the kid's room. Voila!