Lactarius trivialis is a species of mushroom belonging to the lactarius genus. The fungus is most commonly found around Great Britain and Ireland. The colour of the mushroom's cap can range from a light brown colour, to dark purple. The species has a total of five subtaxa. It was discovered and first recorded in the year 1838 by Elias Magnus Fries, in his book, Epicrisis Systematis Mycologici.