You can buy the UK, French and other European editions of Vogue in the US...check out Barnes and Noble or Borders. If you're in an area where they usually don't carry a specific edition, have them order it for you. We have (mostly) great customer svc. in the US. (no need to bring mags over).
Second the cream crap...my DH and everybody who has visited us hate cream filled crap, and esp. the Easter stuff. We do not eat easter filled eggs here because they are groce. Also hate those mince pies at Christmas...like fruit cake...yuck. Sorry, as I know we eat stuff that you don't like like grits, or greens or some spicy food.
Yes, National Trust gifts would be nice and good English teas. Also, second the comment about cookies...I think english biscuits are plain and don't waste my calories on them, but give me a Pepperridge Farm cookie in the US....I love all the types..and there are hundreds. Also, lots of Americans like to make cookies (biscuits) from scratch so they will always be better than the store bought.
As Americans, here's what we bring to our friends and relatives back home in the US...English teas, jams/jellies, anything Harrods, Jo Malone, Neal's Yard anything...oh yea, and some 'over-the-counter' stuff in the UK that you need a prescription in the US for...amazing how people always want these things....takes precedece over food even