The Box of Texas is also serving as a Package of America-ness: I'm sending her Kool-Aid, Reese's, Jolly Ranchers, and whatever else I can think of that she may not have. I asked her if there was anything she'd heard of that she'd like to experience, and she told me this:
Imogen once brought back these amazingly sour sweets from the US which I thought were possibly the best thing in the 'verse. The fact that I've completely forgotten what they're called may be an issue but they were small, disc shaped and sour.
Do you have any idea what she's referring to?
edit: Additionally, if you are from the UK (or anywhere that's not the US, really), what would you be interested in?