I also feed my Dylan Nutro Natural but am fortunate enough that he has a cast iron stomach and also feed him Natural Choice and a few other foods I found recommended here. He loves the variety (but not all dogs can tolerate this type of feeding) so I mix and match them.
Dylan will try to eat grass, sticks and actually pull up weeds acting like a madman if given the chance. It's a big game to him and I have to carry a toy when we're outside to stop him.
It's not a matter of lack of nutrition for him but his high energy way of saying, let's play, let's play!!