"Except the vine, there is no plant which bears a fruit of as great importance as the olive." Pliny the Elder (AD 23-79).
I would agree, although I am quite partial to the humble strawberry. Vinomaker would disagree: He thinks any land planted to olive trees would be invariably better off if planted to vines.
Our neighbours have formed an olive oil cooperative and today was their olive harvest. I, for one, hope it was successful and bountiful as I enjoy the couple of bottles they give us...olive oil pairs well with wine.