a shower pole,
clothes pins (for his crisps!),
Tupperware,
plastic storage baggies of all sizes.
The shower pole would be too awkward for you to bring over. He should be able to get it from any number of hardware stores (B&Q or Homebase should be near him?).
The crisp bag holders are easy enough got at Target and cheaper so you may as well get them for him, it's probably not much of a bother for you to pick them up and they don't take up any room.
Tupperware type containers you can get here but I'll tell you what are like gold for some American ex-pats - the Glad or Rubbermaid "disposable" containers. I've had mine going on 3 years now and they are great. Lightweight and just the right size for everything. You can pack your socks and underwear in them to save room in your luggage. You can't bring too many over.
Plastic baggies you can also get here however the ranges of choices of types of bags are greater in the states. As it is a little thing there's no harm in you stuffing a few boxes in your luggage.
All of these things are much cheaper in the states so if you can bring them, why not. It's a nice thing to do for him and you don't have to go too out of your way for them, nor will they take up much space or cost you much.
But the shower pole would be a bit more trouble to pack.