It was a goose that laid golden eggs wasn't it, and it was in Jack and The Beanstalk.  I've found myself thinking a lot about that tale recently:
Would a modern Jack have sold his cow on eBay?  Would he have taken Bitcoins for it, or are eBeans even better?  What sort of person sells beans and would trade a handful for a cow?  Did the bean-trader know they really were magic?  Did one ill-judged deal drive Jack to a life of petty theft, stealing geese, harps and the like?  I ended up terribly confused about the morality of the whole story, even though it ended happily for everyone except the giant.