Favorite prints for boys

I'm more a fan of versatile basics than prints (with the exception of liberty of course). HOWEVER, my boy starts kindergarten this fall and dress code dictates that he must wear a collared shirt each day. I thought to make things a little more kid friendly I'd buy a few cute prints for shirts for the school wardrobe. So...what are your favorite prints for boys? He's pretty flexible in terms of gender specific colors but won't wear solid pink. Also, what brands have the best hand and wash up the best? I recently used and liked some cotton and steel but other than that I'm out of the loop. I don't want to end up with shirts that are too stiff.