Would that I were so proficient! But I believe it of you, Athenaeus!
My vote goes to the incredible, edible EGG. What else is such a textural chameleon -- solidifying some foods, making others lighter than air, itself on occasion both liquid and solid at the same time? And nobody has to die for us to use them (except maybe the bugs that the birds eat).
I was hoping someone would say onions. If you're a chef and you've never played with some Vidalia onions....you really should. Heck, even if you aren't a chef you should. I've eaten them like an apple.