Checklist of the British and Irish Basidiomycota (CBIB)
Hosted by Royal Botanic Gardens, Kew
http://www.basidiochecklist.info/
Kew Mycology
http://www.kew.org/science/mycolexp.html
BMS
British Mycological Society
http://www.britmycolsoc.org.uk/
FRDBI
Fungal Records Database of British Isles
http://www.fieldmycology.net/FRDBI/FRDBI.asp
Index Fungorum
Search page
http://www.indexfungorum.org/names/names.asp
Mycokey
Identification app