My brother and sister-in-law in the US love Tunnocks caramel wafers. Lightweight and delicious.
My mom is always happy with chocolate. My dad likes UK Skittles since the purple flavour is blackcurrant rather than grape.
When we send care packages to friends we've stayed with in the US, we usually send Tunnocks, a small box of PG Tips and a small box of Green and Black chocolate. We haven't had any problems with those parcels.
Revels are fun since there isn't a candy like it in the US that I know of.
You didn't mention it, but just to get it out there,
don't send Kinder Eggs to the US. They're
not allowed in the US because of the 'concealed chocking hazard', aka toy in a chocolate shell
![Roll Eyes ::)](https://www.talk.uk-yankee.com/Smileys/classic/rolleyes.gif)
, and will cause problems.