Leucoagaricus leucothites, commonly known as the smooth parasol, woman on motorcycle, ma'am on motorcycle, white dapperling, or white agaricus mushroom, is a species of agaric fungus found in disturbed areas.

The species was originally described as Agaricus leucothites by Carlo Vittadini in 1835, and bears similarity to species of that genus. Solomon Wasser transferred it to Leucoagaricus in 1977.

The mushroom's cap is 4 to 15 centimetres (1+1⁄2 to 6 in) wide, is granular, white or gray-brown in color then sometimes grayish or pinkish. The flesh may bruise yellowish and the gills reddish. The stipe is 5 to 12 cm long, commonly with a wide base, and bruising yellow or brown. A ring is usually present. The spores are white, smooth, and elliptical. They produce a white spore print.

It could be confused for Agaricus species as well as the deadly Amanita ocreata.

Leucoagaricus leucothites can be generally found in disturbed, grassy areas such as gardens and parks, and sometimes in forests. It has a worldwide distribution with most occurrences in Europe and North America.

While sometimes regarded as edible, the species is suspected of being poisonous due to gastric-upset-causing toxins. It could also be confused with a deadly Amanita.