Here is a brief list of what foods are HEALTHY for your pup to eat and what are HARMFUL. This is not a complete list. The harmful foods have varying levels of toxicity and it is based on how much of the food is ingested.
For example, my 50 Lb. dog ate about six small chocolate candy bars one day and I came home and panicked when I saw the empty wrappers. I called my wife at the time, who is a vet, and she asked me what kind of chocolate, semi-sweet or dark? I told her semi-sweet and she told me it would be OK, semi-sweet isn't as toxic as dark and she may just get a little sick.
The bottom line is DON'T PANIC! Call the vet immediately, but try to determine exactly how much of the food your dog ate first if possible, this is vital for a treatment plan.