The following sites provide information on those things that could be poisonous or harmful to your dog
Foods and other things that may be eaten
Some dogs seem to have a high tolerance of some foods which can be toxic to others at very low levels. Please don’t think that because you, or someone you know, has always fed their dog on chocolate it is safe because another dog may need veterinary attention after a tiny amount.
Things in the garden
5 Pet Poisons Hiding in your Purse – In all probability none of us would encourage our pets to rummage through our bags but it can all to easily happen if you don’t put them out of reach and it could result in your pet finding something that will harm them. Many people carry chewing gum which if sugar free may contain Xylitol related to sudden and possible fataldrops in blood sugar – (another Dr Becker article)