Peanut butter sandwiches with concord grape jelly on Wonder bread, washed down with root beer.
Quite a few people beat me to the punch… so here’s some stuff I could think of…
Passenger pigeons. (Alas, now distinct.)
Buffalo jerky.
Buffalo wings.
Crawdads.
Ice cream cones.
Boiled custard.
Turducken.
Gooey Butter.
Boiled peanuts.
Coca-Cola.
Vernor’s Ginger Ale.
Dr. Pepper.
Sex On The Beach.
Long Island Ice Teas.
Mickey Mouse Ice Cream Bars.
Moon Pies.
Dagwood Sandwiches.
Pizza Pie, and particularly the pizza-by-the-slice concept.
Salad bars concept.
Peach cobbler.
Muslim Navy Bean Pie.
and about 99% sure almost every popular dish requiring mayonaisse, although mayonaisse itself is a 17th century French invention. So Deviled Eggs, Potato Salads.
Toward the end of compiling this list, I found this website sort of helpful.
It mentioned Gator-Ade, Kool-Aid and Tang, which I kicked myself for not thinking of those first.
Did I just type, “Alas, now distinct?” While technically true, I meant extinct. Carry on.
New World Foods: corn, potato, tomato, bell pepper, chili pepper, vanilla, beans, pumpkin, cassava root, avocado, peanut, pecan, cashew, pineapple, blueberry, sunflower, quinine, wild rice, cacao (chocolate), gourds, and squash.
Most of the things listed in this thread originated here, which I believe is what the OP is after.
BTW: the potato is from South America. 
clam chowder
wild rice
potato skins
rhubarb pie
You can also add wild rice and cranberries to this list. They are North American in origin. Both sweet potatoes and white potatoes are South American in origin, and there is some argument that coconuts are as well. Strawberries are indigenous to both North and South America (Fragaria chiloensis is South American and F. virginiana is North American).
There’s probably more but I can’t think of them now.
Philly cheesesteak.
Crawfish etoufee and gumbo (or is that french?).
Dry rub ribs.
Pulled pork sandwiches.
Alaska king crab.
Grits!
Fried okra.
Red beans and rice.
Blackened catfish.
Oh yeah, and cold cereal (except for muesli) originated here. Where would the world be without Rice Krispies, Corn Flakes, Shredded Wheat and Raisin Bran?
Peanutbutter and jelly
Pumkin pie
Fritos
Chop suey.
Cornbread
Gyros
Deep-fried Oreos
Jambalaya
Crawfish Etoufee
Wonder Bread and American cheese
Hawaiian pizza
Obviously, we’re just trying to think of native American foods here, but think about what kind of restaurant would serve the following all on one menu:
Raisin Bran
Pringles
etouffe
Kool-Aid
peanut butter sandwiches
cheese curds
beef jerky
cranberries
corn on the cob
corn dogs
fortune cookies
Fresh-fried potato chips. Invented in a moment of sarcasm.
I went to college in New Orleans, and I think I can honestly say our campus cafeteria. It wasn’t exactly KWIZ-EEN!
Ok. Thanks everyone for the ideas; keep them coming.
I see a distinction between indigenous plants and
animals to N. America and dishes that are uniquely
N. American. I was thinking of both, actually. So,
this is what I have on the menu:
Breakfast:
Plain or blueberry pancakes with rich maple syrup
from Quebec, the Gaspesie and Northern New England
Grits, steaming hot with a pat of butter
Corn Flakes or shredded wheat with milk
Lunch:
Grinders with various combinations of meats
Philly Steak
Hamburger or Cheeseburger
Grilled cheese sandwich
Hot Brown
BLT sandwich
Dinner Entrees:
All entrees include a visit to the salad
bar.
The Thanksgiving plate:
Roasted turkey with cranberry sauce. Comes
with squash, sweet corn, green beans and
pumpkin pie.
The New Englander:
A bowl of clam chowder, accompanied by a
sampler plate of lobster tail, clams
and mussels with garlic butter. Served
with your choice of carrots or peas.
The Texan:
Chili con carne (indicate mild, medium or
fire-alarm spiciness), roasted jalapenos
stuffed with jack cheese, and corn chips
with guacamole dip.
Mother’s best:
Mouth watering meatloaf, served with
steaming mashed potatoes, greenbeans
slowly cooked in butter and ham hock.
Cajun Combo:
Shrimp gumbo, with a platter of blackened
catfish, cornbread and black-eyed peas.
The Fish Fry:
Batter-dipped Boston Scrod deep fried to a golden
crisp. Your choice of two: Baked beans, potato
salad, or cole-slaw.
The Pic-Nic:
Your choice or pulled pork or beef barbecue or
fried chicken, corn-on-the-cob, and a side of
waldorf salad.
The Canadian:
Poutine, dulce, [meat and veggie]
Sides:
Fried green tomatoes
Fried cheese curds
Buffalo Wings
Wild rice
Zucchini, carrot, pupmkin, banana breads
boiled or roasted and salted peanuts
Children’s menu:
PB&J or PB&H
Mac and cheese
Beany-weenies
Desserts:
Apple, peach, key lime, rhubarb, derby pies
Strawberry shortcake
Peach, apple or blueberry cobbler
Watermelon slices
Brownies
Smores
Nanaimo bars
Drinks:
Coca-Cola, Pepsi, sweet tea, steam beer,
micro-brewery beers with hops from the PNW,
California and Mid-West wines.
crab cakes
soft shell crab