Hygrophorus eburneus, commonly known as the ivory waxy cap or the cowboy's handkerchief, is a species of edible mushroom in the waxgill family of fungi. Hygrophorus eburneus is the type species of the genus Hygrophorus. The fruit bodies are medium-sized, pure white, and when wet are covered in a layer of slime thick enough to make the mushroom difficult to pick up. The gills are broadly attached to the stem or running down it; as the family name suggests, they feel waxy when rubbed between the fingers.

It is widespread in Europe and North America, and has also been collected in northern Africa. Like all Hygrophorus species, the fungus is mycorrhizal—having a symbiotic association whereby the underground fungal mycelia penetrate and exchange nutrients with tree roots. They are common in a variety of forest types, where they grow on the ground in thickets or grassy areas. A number of biologically active chemicals have been purified from the fruit bodies of the fungus, including fatty acids with bactericidal and fungicidal activity.