The vet said that catgrass wasn't good for her.
I really think having it readily available would help with that "OMG I MUST EAT EVERY LEAF" compulsion she has. She did throw up a lot when we grew catgrass awhile ago, but like you said, she may have needed it to get rid of her fur ball.
I have most houseplants out of reach, but I don't grow anything in the lily family because of the toxicity.