Shades of Amelia Bedelia...
From reason.com:
None of these reports say where or when this purported prohibition took place, other than those vague references to California and the '90s. A Lexis-Nexis search turned up nothing. I asked the American Library Association, which sponsors Banned Books Week and keeps track of such things, if they were aware of such an effort; they told me it wasn't in their database. Metro said it got its info from a book called Seuss Facts, which as far as I can tell does not exist—though a Facebook feed by that name did mention the alleged ban without citing a source. I got in touch with some of the other reporters and bloggers who had repeated the story. None of them were certain where it came from. After I contacted BuzzFeed's Spencer Althouse, who included Green Eggs in a banned-books list last year, he concluded that the story was "a terrible, terrible rumor" and added a correction to his article. I'm open to the possibility that there's a real event here that I haven't been able to track down, but that seems extremely doubtful.
Besides, I'm pretty sure I know where this began. It's my fault. Sorry. My bad.
(via BoingBoing)
Related: The Amelia Bedelia joke edit that fooled Wikipedia (and beyond) for five years.