My favourite treats stateside are Lindor Milk Chocolate Truffles with Sea Salt. However, if you ever get to Ireland at some point, Butler's Irish Creme chocolate bars ain't too shabby either.
(Having been raised in Canada, I figure I should be coming out with some kind of amazing Canadian confection. I'm drawing a blank right now, but there has got to be some. Every time I think of Canadian treats, I get stuck on Hickory Sticks and can't move past them. They are my absolute favourite salty snack!)
See's. If 26 million pounds of candy is considered mass produced.
Peach rings. Yummmmmmmm.
I've driven by their factory in South San Francisco. It's pretty big. I hear that their Los Angeles factory is even bigger. They don't make their own chocolate though. Their biggest chocolate supplier is Guittard, which is nearby in Burlingame. I've seen some places selling bulk Guittard chocolate.
Still - I believe the OP was thinking of candy that you might find at a supermarket or maybe Target. See's is kind of a specialty candy and not necessarily available throughout the US.
The individually wrapped Resses Mini-cups.