I'm sorry to see you going!! We'll miss you.
I like taking crumpets home. They don't last as long as some things, but they are hard to find in the states.
Many of the other things I like are more regional to Wales, bara brith, for instance. Also, I don't know if you've had it, but I've picked up a bit of a habit with lemon curd. I like taking that for family in the states. It's like lemon meringue pie on a slice of bread, yum.
Outside of those things, most of my new favorites are things I've learned to cook myself, so I can do them back home too. Good luck deciding, and best of luck with the move. I don't envy you the process. I'm still unpacking here (and I've been here for four months!)