They'd want our coconuts, I bet. They're pretty cool, I bet aliens don't have coconuts. They might have some cool alien fruit to trade for coconuts. Or weed.

Larry Niven and Jerry Pournelle's Footfall had that as a plot point. The youth of the alien invaders who were born on the ship and had never lived on a planet disagreed with the others about invading Earth as the stuff they need can more easily be found on Saturn's moons