Kid Dracula (GB) - The chicken boss drops eggs that hatch into chicks.

RoboTrek (SNES) - Only if ones you can't actually see count: Early in the game, check the birdhouse by the father's house. You'll get a dialogue box that says you can see an egg. Check back later and you'll get a box that says the egg has hatched. Keep checking back and it'll describe the bird in various stages of development until it finally flies away.

Final Fantasy Adventure (GB) - My memory is a bit fuzzy on this one, so if I'm wrong let me know. But I think I remember that the Chocobo you get hatches out of an egg. Edit - this is correct. I looked it up in a FAQ.

Harvest Moon (SNES) - Again, this is only if ones you can't actually see count: Your eggs can hatch into more chickens if you keep them.
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They make no difference" - One For One
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