Regardless of where you're going, local specialities are always good: the kind of thing you'd have trouble finding even elsewhere in the US. Some ideas:
- cookies, especially the giant, (pseudo-)handmade, chewy kinds like Pepperidge Farm
- candy, eg. Reese's Pieces and other peanut-buttery things rarely seen outside the US
- liquor, eg. bourbon or Californian wine
- clothing from local sports teams, eg. sweaters or baseball caps
For the two-year-old, you could do worse than the "Good Night X" series of picture books, they've got one for most American states and major cities.
Towels would be... bizarre. They sell plenty at IKEA, and they're from the same Bangladeshi factories as yours.
(Disclaimer: I'm Finnish, not Swedish. But we're close enough.)