Hi Nemo,
Rhubarb leaves are toxic to everyone and everything, we did not even feed them to the chooks (and those guys used to eat just about everything).
Grapes and dried fruits do cause renal failure, it is best not to test how much your dog can eat, just in case you give more and have to make an emergency dash to the vet at all hours.
Our boy loves a mixture of veg but his favourite at the moment is sweet potato and zucchini all mashed up together. He loves most fruits too (apple, pear, banana, rockmelon and watermelon)...
Thank you Staffyluv
See I am learning
-Nemo ;)