I'm happy to report that two of my sketchbook drawings, above, are to be included in the un-humbly titled Strokes of Genius 4: Exploring Line, published next year by North Light Books. I'll revisit this when the book actually comes out. There were 112 artists chosen for inclusion out of 1650.
The top drawing is in pencil, and was done while I was waiting for a burger at a restaurant. The bottom one was done with a Sharpie. The sprawling oak tree was in a field. You can click on them to see them larger.