I love shooting the way you described it. My grandchildren love to shoot... the target gets old quick, but they will shoot at ping pong balls, sticks and leaves... all day long.
The other day my grandson stuck a somewhat rotten stick into the top of my block target and we had a blast. Glanced several off of the stick and broke it into several pieces. He even set his iPhone up and took close up video to slow down the action.
Great fun!!!
Another favorite is using flu-flus to shoot flying discs (frozen pizza cardboard circles glued together), sycamore seed pods, walnuts, etc.