This time of year, in your location, annual rye grass seed would probably grow really well. And it grows fast, too. My sullies also love hibiscus flowers and leaves. (I think they're called Rose of Sharon plants in some other parts of the country, but don't quote me on that.) Also, you can buy a big bag of "tortoise seed mix" online that's basically a mix of dandelions and other broad-leaf weeds, as well as kale and other leafy greens. Some people are into growing spineless prickly pear cactus for their torts, but I think it's a really annoying plant, and my torts don't even like it, but some people swear by it...