Hmmmm...I find that pretty ironic since my dogs have access to woods (a state park) every day with a variety of foliage, berries, grass, and bark<?>, and they have never once tried to eat these things as part of their daily meals even when they were on kibble.
All of the research that I have read supports the fact that WE are omnivores with teeth and mouth structures to support these facts and DOGS are carnivores with teeth and mouth structures to support that also.
Also, dogs must have a different digestive system than us otherwise they wouldn't be able to eat he rotten things they do (like trash!) and live through it
Oh, and a side note...I had a puppy get in the bag of potatoes yesterday and munch on one....he promptly vomited it all back up. If he was designed to eat that sort of thing, why would his body discard it? Same thing with grass?