A groat was a Cardassian foodstuff that, among other things, served as the base for groatcakes. (DS9: "The Magnificent Ferengi")
Odo once remarked of Ferengi that they would sell their own flesh and blood for a Cardassian groat. (DS9: "Necessary Evil")
In 2374, Quark came to Odo's office to speak with him about a missing shipment of groat clusters. (DS9: "His Way")
According to the Star Trek Encyclopedia, 4th ed., vol. 1, p. 319, groat was the "grain of a cereal grass widely cultivated on Bajor and providing a flour for baked goods such as bread and pastries."