Things that are poisonous to pets
It’s not just chocolate and onions, but also grapes and a whole host of other things that are edible for humans but not for dogs and cats. Very useful to information from petalia.com.
Also, other common household products that you should keep away from pets.
More about grapes and raisins, which can cause renal failure in dogs.
And here’s a really comprehensive list from the ASPCA.
Also, here are some outdoor plants that you shouldn’t let your dog chew on in the garden.