This is documented in the Mahaparinibbana Sutta's story about the meal containing sukara-maddava served by Cunda to the Buddha, which is presumed to be the cause of dysentery experienced by the Buddha.
The Mahaparinibbana Sutta is sutta 16 of the Digha Nikaya of the Sutta Pitaka of the Pali Canon, which is the sutta explaining the events leading to the Buddha's passing away and events that occurred after that.
The Pali Canon is the authoritative canonical scripture of Theravada Buddhism, and is an Early Buddhist Text. Please read this answer for details.
In this footnote, sukara-maddava is explained:
Sukara-maddava: a controversial term which has therefore been left
untranslated. Sukara = pig; maddava = soft, tender, delicate. Hence
two alternative renderings of the compound are possible: (1) the
tender parts of a pig or boar; (2) what is enjoyed by pigs and boars.
In the latter meaning, the term has been thought to refer to a
mushroom or truffle, or a yam or tuber. K.E. Neumann, in the preface
to his German translation of the Majjhima Nikaya, quotes from an
Indian compendium of medicinal plants, the Rajanigantu, several plants
beginning with sukara.
The commentary to our text gives three alternative explanations: (1)
the flesh from a single first-born (wild) pig, neither too young nor
too old, which had come to hand naturally, i.e., without intentional
killing; (2) a preparation of soft boiled rice cooked with the five
cow-products; (3) a kind of alchemistic elixir (rasayanavidhi).
Dhammapala, in his commentary to Udana VIII.5, gives, in addition,
young bamboo shoots trampled by pigs (sukarehi maddita-vamsakaliro).