haystack

A mound, pile, or stack of stored hay.
A standing wave in a rapid.
The text string within which another string is searched for. (see: needle in a haystack)
(broadly) Any place or collection of items through which one searches for something that is rare and hard to find.
A dish composed of a starchy food (rice, tortillas, crackers, etc.) topped by a protein (beans, cheese, meat, etc.) in combination with fresh vegetables, assembled on the plate by the diner.