Good comic but don't feed bread to ducks.

TL;DR:

Here’s a great list of safe-for-waterfowl foodstuffs, which include cucumber, corn, peas, beans, broccoli, beets, squash, flowers, alfalfa, tomatoes, eggplant, bananas (no peel), pineapple, pomegranate seeds, scrambled eggs, dry cat food or dog food, and rice