Lay out bread slices; spread 4 slices with peanut butter and the remaining 4 with jam. Cut banana into slices and place on top of the peanut butter. Close sandwiches and cut off the crusts. You can also use a cute sandwich cutter or cookie cutter here if desired.
Add a sandwich to each lunchbox, along with a serving of all remaining ingredients; keep dressing in a separate, smaller container until ready to eat.