I started 1st grade in 1953.  My grade school did not have a cafeteria so in good weather I walked home for lunch & in bad weather my mom packed my lunch.  My favorite lunch box sandwich was either a balony or vienna sausage sandwich, squirt of mustard on 1st slice of bread, balony or vienna suasage, lettuce, mayo,bread.  I loved how the lettuce got limp & everything was slightly warm by noon time.  Now I know that for most folks a warm, limp sandwich is not appealing, but waht can I say I love it.   I still will make a sandwich in the morning, wrap it up, leave it out & eat it for lunch.  Also, before anyone asks, no food poisoning after eating sandwiches this way for over 57 years.