Thanks to my awesome photo skills, you too can make your own :)
Plywood (cut to the size you want your headboard to be—mine rests on the ground, so it's biggish)
Fabric (we used a twin bottom sheet—I cut the elastic out)
1. Lay out all the batting in layers slightly bigger than the board; place board on top
2. Feel pretty awesome about using a staple gun to secure batting to board
3. Feel less awesome as you struggle with the contours of a fitted sheet
4. Regain staple-gun awesomeness. Work hard to make the corners neat and tidy. Realize no one will ever see this part, and take a picture so others can appreciate it.
5. Flip it all over, and start drawing on your "headboard" with a sharpie. Realize you like drawing with sharpies, even though you have to be careful because, well, it's a sharpie.
6. Oh yeah baby—headboard! Revel in its charm (read: imperfections). Revel!
7. Call in Miss Lu. Observe gratifying reaction. Consider using sharpie on other surfaces. Reconsider.