I'm so glad you also added in the bit about what NOT to feed dogs. A lot of people don't realise that some veggies and fruits that we love to eat are harmful to our companion animals. The amount of times I've had to explain why feeding dogs and cats garlic regularly is NOT a great way to keep ticks and fleas off them is frightening. Also chocolate, because there are "chocolate" dog treats on the market - which are actually made from carob, not chocolate - people think it's okay to give their dogs chocolate, but it's also highly toxic to dogs and cats. Bit of side trivia: chocolate is also very slightly toxic to us as well, but we'd have to eat something like 11kgs of the stuff in a short span of time, like less than a few hours, to die from it. Which brings me to the point of the poison is in the dose. If you drop a grape on the ground and your dog snatches it up and eats it before you can react, don't worry about rushing him off to the vet, it won't kill him. Just don't let that happen too often and definitely don't let him get hold of and eat a whole bunch of them. And it's not just cats and dogs to be thinking of. Some lettuces, such as iceberg lettuce, is bad for rabbits. Horses shouldn't eat tomatoes, avocados or anything in the onion family either. Broccoli is harmful to goats. Raw/uncooked beans are harmful to chickens. The list goes on.
Also be wary of dogs around your veggie patches, not just because they will sometimes decide to eat things that taste great but aren't good for them, but also because once they figure out that things like carrots are good and they grow in the dirt, all that dirt could end up dug up and those carrots you've been tending to could be eaten!