Chocolate is poisonous to dogs, but the dosage in a brownie or something
probably isn't going to be that bad unless they're tiny.
Pot, on the other hand, can cause some really awful effects even at small doses. I've seen and heard a few stories lately about dogs experiencing real paranoia and longish term personality changes after ingesting pot. I don't know how credible they are, of course, but it's something I wouldn't want to risk.