which came first: the mushroom or the egg?

no matter how deep a sale i can find on sliced mushrooms, i never buy them. generally, they look awful and not fresh at all.
i understand the impulse to buy them--because of the structure of mushrooms, they can be difficult to cut into uniform pieces...and pieces uniform of size result in pieces uniform of texture when cooked, which is extremely important.
the day i first cut a mushroom with a hard-boiled-egg-slicer remains a banner day in my culinary existence.