Ok, after some research and a call or two to the parents, we are down to two main possibilities:
1) Maiers Bakery Doughnuts, a local chain in Reading, PA
2) Stroehmann Bakery Doughnuts, a local chain in Lititz, PA
It's a testament to how local these chains are that google.images doesn't have any pictures for their doughnut products, so I can't confirm either of them that way.
But, next weekend is Mother's Day, which means I'll be up in Lancaster, which means I can do some first-hand investigation, and bring back some samples!