My goodness ! ! It does sound like your cat is crazy about grass, way beyond the normal grass chewing that both dogs and cats usually do. I think that in this case, asking your veterinarian about why she is doing this, is definitely in order.
I am still thinking that there is some sort of a mineral or vitamin deficiency that is causing the obsessive grass-eating; but I don't know what she might be short of. it sounds like you are feeding her an excellent diet. She would actually get some vitamins from the grass just by chewing it, eeven though it doesn't really digest properly.
Another possibility is that your cat thinks that the grass is a sort of toy for her to chew and play with, especially since you said she drags it out of the dirt and chews it up. Maybe, this is kind of a "substitute mouse" for her, that she loves to catch and "eat" when she gets a chance. Cats are very ingenious when it comes to their playtoys; so I can see this as a possibility maybe ??
