Tree nuts in general are toxic to dogs. Peanuts are legumes, not "nuts" and are safe (peanut butter being an awesome great and perfect for putting in a Kong)
It is also a bad habit to let her chew things like that because even if you happen to have plants that are not toxic, A)not everywhere else will have safe plants and B) out in public, many people spray pesticides, fertilizers etc on the grass/plants which can be dangerous too