The Buddha died of dysentery after eating his final meal. Specifically what that meal was is unknown, but the traditional account says it was spoiled pork. Some people (including many Westerners who are uncomfortable with the idea of the Buddha eating meat, even though his meat eating and his explicit rejection of requiring monks to be vegetarian is discussed in the Pali Canon many times) have decided that the dish, ambiguously called “pig’s delight” (sukaramaddava) was actually a type of mushroom and he died from poisoning. The article “Pork? Mushroom? How the Buddha Died” discusses this issue. Regardless of what the food was, the Buddha knew that it was bad and would cause his death, so he made sure he was the only person to eat it and had the leftovers buried.
This episode of his life is seldom depicted in Thai temple art and Wat Yang Tuang Wararam (วัดยางทวงวราราม), also known as Wat Ban Yang (วัดบ้านยาง), in Amphoe Borabue, Maha Sarakham province is the only place I can remember having seen it.