Owning torts seem to go hand in hand with gardening. The safest plants I have for my torts are those that I grow from either seeds or cuttings. Once you get the hang of things, you quickly find that you have more plants than you know what to do with. If you live near Baltimore, I have tons of tort-safe plants to spare.
If you end up buying well established plants from your local home improvement store, make sure you wait a while to introduce it into your enclosure. Some people wait 6 months, others over a year. And make sure the plant soil doesn't contain perlite (the white ball looking things that normally help with drainage).