Odour can be very characteristic, but there is great variation in the ability to detect odour, and in the names given to odours. Odours of fungi are usually characterised by comparison to those of other things, such as vegetables; but sometimes specific odours can be recognised, such as that of phenol (a compound present in some species of Agaricus).

Crush a piece of the pileus to intensify the odour, which may also be stronger when the fruit-body is warmed (such as after being carried in a container in your pocket).

Human scent receptors are rapidly saturated, and odour can seem to disappear (the ability to smell the odour will come back after a while). Some odours are difficult to characterise, but the range of options provided here covers most odours that will be encountered among agarics. Some odours are pleasant when faint, but unpleasant when strong, and some of the categories grade into one another (choose more than one option if unsure).

Choose this state if: there is no distinctive odour or if the odour is mushroomy. Other terms for a mushroomy odour are fungoid and fungussy, and a yeasty odour (like bakers yeast) is also included in this category.

Mushroomy is the pleasant odour of the cultivated Button Mushroom (Agaricus bisporus) or the Field Mushroom (Agaricus campestris).

An earthy odour is also included under this character state.

Because some people cannot smell some or all odours (or your nose might be out of action due to a cold), all taxa are scored as having no distinctive smell, which means this state has no diagnostic value.