The shells and sea rocks they had picked together while walking side by side on a beach in South Carolina. The wheat was from a stalk in Kansas that they drove by on that one wild spring break cross-country drive. The screw had fallen out of her chair in that shared gen-ed class, causing the whole thing to collapse right as the other girl walked by (she had saved the coffee, but not the fair maiden, whose bruise lasted weeks). The cord was for her computer science major; the apple for her botany major. And they both agreed that that particular perfume was the best-smelling one in the whole mom-and-pop shop they stopped in on a whim.
They buried the memory-box in the garden on the day they bought their first house.