Wheat

Wheat was a grain-based food staple found on Earth.

By 2018, the "great Canadian wheat plains" had become, according to Ramón Salamander, the main source of grain on the entirely of Earth. (TV: The Enemy of the World)

After being sent to find the Third Doctor, Private Campbell's disfigured corpse was discovered near a field of wheat in which the image of his face had been created. The Brigadier later saw that the face of the Doctor had likewise been sculpted in wheat. (AUDIO: The Rings of Ikiria)

In 1895, all of Alain and Simone's wheat crops failed due to an underground alien bulb which had feasted and grown by extracting all the nutrients from the soil. (COMIC: The Mutant Turnip)