Extremely random question

Who decided we should eat lettuce? I mean, I have nothing against it. It doesn't taste bad. In fact, it doesn't really taste. But who decided it should be on the menu? Did some ancestor way back take a stroll through the garden and think, "Wow, here's a weird kind of ball-shaped plant. Isn't that strange? Let us eat it. I'll call it... let us. Yes, what a good idea!"

It probably wasn't the same ancestor that said, "Ooh... here's a plant with pretty flowers and waxy leaves. Oh, Leander, don't you think we should eat it?"