Recent studies attribute the domestication of Japonica Rice to the Aleut people ~ it was developed in Coastal Alaska and taken to Asia in later centuries.
But right off the bat you have two great starch sources ~ potatoes and corn ~ as well as BEANS and SQUASH.
There are thousands of varieties of each ~ and there are numerous other species that were domesticated by Indians thousands of years ago.
The whole planet has but 6 known centers of plant domestication ~ one is the East Central region of North America (centered on Mammoth Cave) and another consists of the highlands of Central America (Mesoamerica) with a wide variety of climate zones arrayed vertically.