To be sure. Our throats and stomachs are lined with solid gold, and we find the thistles nourishing and good to eat. As a matter of fact, there is nothing else in our country that is fit for food. All around the City of Thi grow countless thistles, and all we need do is to go and gather them. If we wanted anything else to eat, we would have to plant it, and grow it, and harvest it, and that would be a lot of trouble and make us work, which is an occupation we detest.

The Lost Princess of Oz, Chapter 9, "The High Coco-Lorum of Thi" - Later Oz novels