I have seen the French's mustard you guys like there too as well as the products everyone else has mentioned. My husband also loves the Blueberry muffins from the bakery, I know they are not American, but he is fussy about Muffins!
I
love Waitrose and do all of our shopping there, apart from when we get our Farmer's and French Markets, yes I do pay more than if I chose Lidl's for example, but I am paying for ethical, traceable farming and quality.
Just as an aside for those that like ham, they do Duchy Estates organic smoked ham and it is simply the most delicious, dry cut of ham I have ever had, it's dear (runs about £4-5 for 4 slices, but it is so lovely it can make a meal just with something simple on the side. Hubby has been in hospital this week and hated the food, so I was adding to Waitrose's share prices significantly this past week with this ham!
Another tip is their pkts of New Zealand Rib Eye/Sirloin steaks, approx £12-15 for 6 individually wrapped steaks and a really nice quality meat.
I will truly miss Waitrose (and M&S, but that's another whole thread I am sure we have done before!) when I leave,