Since I haven't seen a full listing of the transcon Y options:

Transcon A321T Y complimentary breakfast options (observed LAX-JFK, although I imagine it is the same both ways like lunch/dinner)

* Bagel with jam and cream cheese + small chobani yogurt (admirals club-size) and granola
* Overnight oats with blueberries and almonds
* Fruit & cheese with crackers and dark chocolate square (the standard Y domestic snack)

And the typical lunch/dinner options:
* Sandwich with chips and brookie - components vary...sandwich [e.g., turkey, curried chicken], chips [e.g., baked green pea, sun chips], brookie [e.g., cinnamon, chocolate]
* Hummus and vegetable sticks
* Fruit & cheese with crackers and dark chocolate square (the standard Y domestic snack)