I am not sure that anyone has compiled a list as such, but you can start with nasturniums, pansies, hibiscus, and dandelion (and the leaves of the latter two)....just make sure that anything you use is
completely free of herbicides (weed killers) and pesticides.
My redfoots get a wide variety of fruits, veggies, and occasional earthworms as well as nasturniums, pansies, and dandelion (I cannot grow hibiscus to save my life, for some reason).
You also cannot go wrong with any information you find on this site:
http://www.tortoisetrust.org