I have to look up safe hay/grass for the tiels- you could make toys (braiding it is a good idea)for chewing but don't provide it loose since they will try and use it for nesting. That's if you don't want to breed. I'll try and find something on it. BRB
EDIT: ok- from what I found Western Timothy Hay, Orchard Grass, Alfalfa are safe.
EDIT: ok- from what I found Western Timothy Hay, Orchard Grass, Alfalfa are safe.