It says that if the dog gobbles the grass in great hunks, the blades may cause vomiting:
A dog will seek out a natural remedy for a gassy or upset stomach, and grass, it seems, may do the trick. When ingested, the grass blade tickles the throat and stomach lining; this sensation, in turn, may cause the dog to vomit, especially if the grass is gulped down rather than chewed.
That's one of Penny's techniques.
But sometimes she grazes like a cow, and a couple of days later the grass will come out the other end, folded up neatly. If we come across the resulting 'thing' lying around in the backyard, it's almost impossible to tell which end it came from. On the other hand, the noise of her vomiting a mass of folded grass will usually bring a family member running to see what the uproar is, so we usually know what has happened.
The article also says:
Whatever the reason may be, most experts see no danger in letting your dog eat grass. In fact, grass contains essential nutrients that a dog might crave, especially if they're on a commercial diet. If you notice that your dog has been munching away on grass or houseplants, then you may want to introduce natural herbs or cooked vegetables into their diet. Dogs aren't finicky like cats, but they're not too fond of raw veggies either. They're kind of like big furry kids that way.
That's Penny too. She loves vegetables and fruits, cooked or raw. The only one she turned her nose up at is celery. Of course, we never give her grapes or onions. Too dangerous, by all accounts.
BTW, If you do follow the link to PetMD, the long list of comments are very interesting. Lots of people's experiences with their dogs eating grass, vegetables or fruit.