Not sure about toxic, but my girls avoid onions, hydrangeas, garlic, basil and marigolds. They're not too fond of my daylilies and asters but they gobbled the rhubarb, which surprised me because I thought rhubarb leaves had too much oxalic acid and they wouldn't eat them.
As for the tomatoes, mine would stuff their crops to bursting with 'maters! I've got about 20 last years' canning jars of tomatoes in the basement I'm planning on giving the chickens as treats later this winter when there's nothing green available.
Any kind of squash, zucchini, eggplant, peppers, spaghetti squash, beans, corn... more yummies!