Egg salad
Peanut butter and banana
Pimiento cheese
Ham and Swiss
Bologna and Cheese
BLT
roast beef, lettuce and Miracle Whip
tuna fish
chicken salad
deviled ham
Nutella
Vegemite (there was even a song about it…)
Salami (“summer sausage”), lettuce, and mayonnaise.
Tuna or chicken salad and lettuce.
Corned beef and/or pastrami on rye. With deli mustard and a kosher pickle.
Montreal smoked beef on rye. With deli mustard and a kosher pickle.
Leftover roast beef/roast pork/roast chicken/roast turkey with lettuce and mayo.
Deviled ham, lettuce, mayo.
Liverwurst, lettuce, mayo.
Peanut butter and jam.
Club sandwich. On buttered toast with mayo.
Poor boy/Submarine/Torpedo/Grinder with the works!
Deviled ham on sourdough bread with sun-dried tomatoes, chipotle hot sauce, jalapeno summer sausage, aged cheddar, and butter.
That’s my sandwich today, anyway.
PB&J
PB and honey.
Cheese and honey.
Pulled pork (with coleslaw)
Cream cheese and jelly or cream cheese and olive (what I had almost every day in elementary school)
Here’s the list so far in case somebody would be interested in doing a poll! 
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Egg salad
Peanut butter and banana
Pimiento cheese
Ham and Swiss
Bologna and Cheese
BLT
roast beef, lettuce and Miracle Whip
tuna fish
chicken salad
deviled ham
Nutella
Vegemite (there was even a song about it…)
Salami (“summer sausage”), lettuce, and mayonnaise.
Tuna or chicken salad and lettuce.
Corned beef and/or pastrami on rye. With deli mustard and a kosher pickle.
Montreal smoked beef on rye. With deli mustard and a kosher pickle.
Leftover roast beef/roast pork/roast chicken/roast turkey with lettuce and mayo.
Deviled ham, lettuce, mayo.
Liverwurst, lettuce, mayo.
Peanut butter and jam.
Club sandwich. On buttered toast with mayo.
Poor boy/Submarine/Torpedo/Grinder with the works!
Deviled ham on sourdough bread with sun-dried tomatoes, chipotle hot sauce, jalapeno summer sausage, aged cheddar, and butter.
PB&J
PB and honey.
Cheese and honey.
Pulled pork (with coleslaw)
Cream cheese and jelly or cream cheese and olive
Some British staples:
Cheese and onion on a bap.
Chicken and mushrooms on a bap.
Marmite on white bread.
Tinned beef on white bread.
Bacon buttie.
Grilled steak! :o
Stewart Sandwiches: Chuckwagon, Cheeseburger, Chili Cheese Dog. All warmed in an infrared oven!
Salami Sammitch has, of course, been mentioned. But not my particular arrangement. I used to look forward to the best part of my schoolday, lunch, becuse I knew I had:
Salami on toasted rye topped only with grated parmesan cheese.
By lunchtime Mama’s pineapple on white bread sandwich had already leaked through the bread but it was mighty tasty anyway. Another variation she used was cream cheese with chopped pecans.
I don’t see them much anymore but cooked grits made into a little patty and covered with bacon and a fried egg on white bread was good long before the fast food places started copying those home cooking goodies.
For true connoisseurs no recipe book can beat White Trash Cooking – by Ernest M. Mickler for both good eats and good humor. A true jewel!
Unless I’m misunderstanding the subject line, might it be easier to list sandwiches that do NOT fit?
Go for it!
Now that I think about it, with my understanding that literally ANY sandwich could be eaten for lunch, is that any better?
IOW, please clarify how this thread isn’t “list possible sandwiches.”
I’m afraid to think of such a sandwich. But there must be something that is just too declasse to be put into a lunch box. I did think of one that was more or less a specialty of my Grandmother’s: a big slice of meatloaf with a big slice of Vidalia onion on toast with ketchup and mustard. The sort of thing that Cracker Barrel is probably serving somewhere. 
I was more thinking of the sorts of sandwiches we would have encountered in our school lunches when our mothers wanted to surprise us. Of course you can treat the topic any way you wish.
American cheese, lettuce, mayo on Wonder Bread.
Doesn’t get anymore basic than this! :o
Oh, yeah?! How about three slices of white bread; nothing else? A bread sandwich! No lie, we used to love them!
Has baloney already been mentioned? :dubious: