Many 1970s era ultralights or hang-gliders.
Sorry, I should have maybe used some appropriate emoticon. My point is that any wing has an upper surface, even if it's just the top of the lower surface (hence the remark about monopoles). So the question is completely meaningless. It seems to be a barely-disguisued variation on whether it's the pressure difference or the downwash that generates lift. Answer: since it's physically impossible to generate one without also generating the other (using an aerofoil), the question doesn't make any sense.
Of course if you take a normal wing and simply strip the top covering, it will make an extremely BAD aerofoil, and will not generate lift very efficiently. But it will still have a (rather bumpy) top surface. But as others have said, a single sheet of material, correctly shaped and braced, makes a reasonable aerofoil.