Being in Michigan, cottonwood grows everywhere. It's an ugly and boring wood, just like a plain piece of pine. Soft and wet, messy as can be with all the cotton clogging up the A/C unit and the filter in the car and the branches and leaves blow off every time the wind blows or a rain drop falls. I have never seen one with a Burl on it. The bark can grow nice and thick and carves great, and makes an ok pen. Your Burl pen looks fantastic. I'll have to keep looking for one. I don't know anyone that doesn't want their cottonwood tree leveled!