Well, you have quite a lot of information here, unfortunately not all the posts agree about your solution.
My dogs also like greens, and will happily crunch on a stick of celery or a cabbage stalk.
I wouldn't worry about it either, if as some of the other posters have said, there are no chemicals on the grass, which you can't really be certain of if it is a public place where you are walking her, and that is the problem.
I feel that if she is doing it as much as you say when you are out walking with her then that is slightly strange behaviour, the vast majority of dogs will be way more interested in all the new smells and the fun of the walk than in eating grass!
Perhaps there is a deficiency in her diet, and you should consider changing to a different dogfood, or see your vet and get his advice on the matter.

Hi, have changed her diet to wainwrights which is a more wholesome dog food no chemicals additives and suitable for sensitive dogs (which she isnt) but it is good stuff, and still she does it.

[Corky/Max]

They’re grazing on grass: is it bad for them?

If your dog or cat grazes on grass that has not been sprayed with pesticides, herbicides, or other poisons, consider it food (as long as she doesn’t throw up on your carpet!). Foods like grasses contain cellulose, which may not be completely digested (and you may see the grass unchanged in the dog’s feces), but they are of great value in helping to maintain the bacterial balance in the intestines, helping the “good” occupants of the gut to survive. Fresh grass also provides chlorophyll, vitamin C, and hundreds of other antioxidants and enzymes. Do not let your dog or cat eat grass that has been exposed to chemicals. If the grass is in the woods, it is probably “clean”. If the grass is part of a farm or suburban “perfect lawn,” try to prevent your dog from eating it (or walking on it).