kuthanii (Stangl & J.Veselský) Kuyper Inosperma cookei, commonly known as the straw fibrecap, is a species of mushroom in the family Inocybaceae.

It produces small mushrooms of an ochre colour, with a prominent umbo, fibres on the cap and a distinctive bulb at the base of the stem.

[9][12] Gills on young mushrooms are whitish, then become a grey-tinged pale ochre before becoming cinnamon yellow.

[11] Inocybe rimosa, the split fibrecap, is also similar in appearance; the rarer I. cookei can be differentiated by the smell of honey and the marginate bulb.

[6] The colouration, as well as the thick stem with a bulb, are features shared by two other species of Inocybe; I. mixtilis and I. cryptocystis.

[13] Another fragrant Inocybe is I. pyriodora, which has an odor resembling cinnamon, or ripe pears in mature specimens; unlike I. cookei, it lacks a bulb at the base of its stem, and bruises a reddish colour when handled or with age.

[14] Inosperma cookei is an occasional to frequent mushroom, found growing in mixed woodland on the ground.

[12] Consumption of mushrooms containing muscarine compounds could lead to a number of physiological effects, including: excess salivation, lacrimation, uncontrolled urination or defecation, gastrointestinal problems and emesis (vomiting); this array of symptoms may also be known by the acronym SLUDGE.

[19] Other potential effects include a drop in blood pressure, sweating, and death due to respiratory failure.