For the most part eating grass, etc is not going to lead to a serious problem. There are some poisonous plants and especially mushrooms but considering how frequently these are available the incidence of significant toxicity is low, consumption of mushrooms from the amanita family would be the exception as these can be deadly. Grazing is mostly a habit and an attempt to help evacuation of the GI tract through vomiting or enhanced propulsion of ingesta through the tract. Sporadic changes in stool character are common but usually self limiting without the need for treatment. If diarrhea or vomiting continued past one day or if her general attitude or appetite are affected please let me know so I can advise.