It's a good idea, and they would make great boss-drops. I also like the suggestion that they could get it from the gnat's den (though if a bluebell wore a hat, wouldn't it probably fall off during the first spin-attack it does? ;P ) .
I'll keep it in mind for future boss drops for now, since it requires quite a bit of implementation - but once that time is there, I'll get back to it. ^-^