That's hilarious, the exact same thing happened to me. I used to draw some pretty interesting stuff while in college.

Then I took some mushrooms with a pen and paper in hand. All I could draw was stupid smiley faces. It was just inane gibberish.

So yeah, I guess there is a bit of a myth about LSD and creativity... at least anything that involves fine motor skills and concentration. In this context it was a creativity killer.