Corn stalks
Corn-on-the-cob, offered by Aunt Adah
Corn was a plant indigenous to Earth. It was a grain used by Humans as food.
Corn kernels, when taken off the cob and dried, were cooked in oil to make popcorn, which was often served at movie showings. (ENT: "Dear Doctor"; VOY: "Repression")
According to her guidebook, Shannon O'Donnell was near a re-creation of The Last Supper made entirely of corn when she was driving through Indiana in 2000. (VOY: "11:59")
In 2151, a Klingon K'toch-class scoutship crash-landed in a cornfield in Broken Bow, Oklahoma. The field belonged to a corn farmer named Moore, who subsequently shot the pilot of the craft, a Klingon named Klaang, after the Klingon destroyed his silo. (ENT: "Broken Bow")
When Subcommander T'Pol chose a farm on the Akaali homeworld as a landing site for an Enterprise away team because of its sparse population, Jonathan Archer remarked "this must be why aliens are always landing in cornfields." (ENT: "Civilization")
In 2371, when USS Voyager was pulled to the Delta Quadrant by the Caretaker and beamed aboard to a holographic simulation of a farm, the crew walked past a garden patch of corn stalks. The Caretaker, in the form of Aunt Adah, offered the crewmembers some corn-on-the-cob and some lemonade. (VOY: "Caretaker")
Three years later, aboard Voyager, Tom Paris noted that a mystery meal prepared by Neelix tasted "vaguely like chicken, but it has the consistency of corn husks." (VOY: "Hunters")