While you kids possibly never had any traditional Polish food at Grandma Rose's house,* I do remember once or twice having some version of Paczki. When she said it, it sounded a little different (like there was an "n" in the word), but that was probably just an ethnic accent sounding on my MN ears.
Anyway, I was just reading Brown Eyed Baker's recipe and the light came on that this is what Grandma was doing! Hers were not filled and were rolled in granulated sugar. She rolled the dough into little balls by hand before letting them rise and I'm positive no actual recipe was involved, but if any of you kids are looking for "a traditional Polish dish that Grandma used to make," this is probably as close as you're going to come (unless we can get Barb to actually write something down someday**).
*I have theories about why, but that's another conversation.
I'm guessing fried cheese doesn't count.
**Not gonna happen.