On an ordinary train ride, the speaker's tongue finds a small hard bit stuck between two molars. It's a leftover from a hurried breakfast at a Brooklyn diner. The molars crack it open, and taste does the rest: rye toast. Suddenly the speaker realizes what that breakfast was. It was "our last meal together."
What makes the poem work is how quietly it handles that realization. There is no outburst, no explanation of who "our" refers to or why the meal was the last. The poem hands us the fact and then stops on a single word, "Caraway seed," as if the speaker is still holding the taste in their mouth. The short lines and plain language feel like a thought arriving in real time.
The mood is hushed and bittersweet. The speaker seems to feel a delayed ache, set off by something tiny and physical. The poem suggests how memory can ambush us through the senses, and how an everyday scrap of food can hold the weight of a goodbye.