Livanian beets were a type of food.
In 2374, Morn received a shipment of Livanian beets at Deep Space 9. After sitting in Cargo Bay 3 for more than two weeks, they had begun to rot.
When Quark inherited all of Morn's assets, practically the only thing of any value he found (prior to the discovery of a thousand bricks of gold-pressed latinum) was the beets, which had gone bad. Quark later offered Nahsk and Krit the beets in addition to thirty per cent of the latinum; Nahsk then told him he didn’t like beets. (DS9: "Who Mourns for Morn?")
According to the Star Trek Encyclopedia (4th ed., vol. 1, p. 483), the "Livanian beet" was a variety of aromatic succulent root of a biennial Livanian herb used as a vegetable.