Quote the Deviantart page:
"The Emperor's Egg is a species of nocturnal, ambulatory fungus that wanders about in deciduous forests of Faerie during late Spring and Summer. When they emerge from the leaf litter, they remain encapsulated in their veils, thus creating their name. When an emperor's egg is ready to spread its spores, its cap and stalk bursts through its veil.
The 'eggs are edible, being so deliciously delicious, and mind-bogglingly sapid so as to drive mortals irrevocably insane with delight.
Although larger fae do eat them, the actual practice of hunting and eating 'eggs is considered a taboo topic. This is because pixies and sprites adore 'eggs as playmates and pets (thus, discussion of eating emperor's eggs is tantamount to discussing killing and eating the family pet in front of children who are armed with sharp, pixie-dust coated weapons). In fact, there is an infrequent practice of politely disposing of unwanted mortals among fae by inviting the aforementioned unwelcomed guests onto an "'egg hunt," only to abandon them to the tender mercies of irate pixies and sprites."
It's worth mentioning that in our world there actually are several types of gallinaceously-named fungi, the Chicken of the Woods, Laetiporus sulphureus, the Hen of the Woods, Grifola frondosa and the Turkey Tail Shelf Fungus Trametes versicolor Then, of course, there's the Bird's-Nest Fungus, Cyathus striatus.