Dogs are scavengers by nature so they'll eat anything they can get their paws on. :)
You should stick to dog food (most brands have pedigree-specific food and suggested portions; if you're getting a mixed breed or mutt, go for the generic type of food). A nice piece of chicken (NO chicken bones; they can harm their liver) or pork chops will be welcome too - avoid red meat though or keep it to a minimum, it can cause itching. Get bones from lamb, etc., at the butcher's.
Avoid chocolate at all costs (it can blind them) and most nuts as well as raisins. If you do give them a piece of cake occasionally, avoid anything made with the sweetener Xylitol.
Dogs usually eat anything that smells or taste nice. Dog food (wet and dry) is what most owners feed them for a dinner/lunch/breakfast. During the day they mostly eat what they can find, grass, roots and other things they find on branches or plants. They also catch a rabbit on the occasion or a bird. Or eats entrails of birds/rabbits cats have caught.
aspca's website has a list of things they shouldn't eat grapes onions chocolate cooked chicken bones its a long list but they can eat alot of the same things we eat but its best to feed a hih quality dog food