Ok, so it's not really a clover (and I still call it The Apple Key). Folklore.org has the story
of how the Finder's menu items (and the Apple keyboard's Command key for that matter) acquired its curious little symbol. It all started with a Steve Jobs rampage (go figure) and ended with a Swedish Campground. Check it out.
Incidentally, Folklore.org is a treasure trove of stories about the early days of Apple and the Macintosh. Spend five minutes reading and you'll be there for an hour.
[Via The Apple Blog