Most amateur naturalists are probably familiar with a small number of common mushrooms and toadstools and perhaps some bracket fungi or puffballs. Fungi are in fact morphologically a very diverse group varying in size from the microscopic to the substantial, occurring as brackets, crusts, jellies, cups, clubs, cushions, moulds and mildews in a range of textures and colours. The part of the fungus we can see is the 'fruiting body' (the part of the fungus which produces the spores) and it is the macroscopic and microscopic characteristics of this structure and its spores which are used when attempting to identify a fungus.
The information on this website should not be used for identification. Most fungi are not poisonous, but you should not eat wild collected species unless you are confident that they are edible.
Not all fungi can be accurately identified at the species level without an examination of the spores and cellular structure of the fruiting body. However, it is possible to identify some species without the use of a microscope by careful examination of the visible features. A successful identification requires attention to detail and a close examination of the structure, size, texture, shape, colour and smell of all the parts of the fruiting body. Other useful features are the type of habitat, the substrate (what it is growing on), the season and associated plants (this is particularly important for woodland species). It is often very difficult to identify a fungus from a photograph, so it is important to make detailed notes in the field, particularly as the colours and textures may change after picking.
There are some excellent field guides and basic identification keys available and help is available from various internet forums and websites. However, the best way to learn about fungi is either to join a local fungus group or attend one of the excellent courses organised by the Field Studies Council.