I've always been interested in fungi. Not from a commercial p.o.v.especially, but just because of their diversity and fascinating characteristics. I'm still mostly interested in edible, or visually arresting non edible and even poisonous species, but I also take an interest in the less obvious species, moulds, etc.
I was raised very close to an ancient woodland area which is still managed and is recorded from the time of the Domesday Book if not before. 60 years ago this wood was little known to 'outsiders', but in more recent times it has been turned into a 'Country Park', and in the last couple of decades I've noticed a decline in the number and range of species seen.
As a kid I was vaguely aware that gathering a couple of species of edible fungi is a long established tradition in Nottingham, and probably in other mining areas. I'm referring to the Field Blewit.. Lepista Saeva, and the Wood Blewitt, Lepista Nuda. Oddly, in my almost 72 years, I have never found any Field Blewitts, but I find Wood Blewitts in many places. including here in the Grand Duchy. I only eat a very few wild species, including Cepes (Boletus Edulis), Blewitts and a couple of others.
My interest in this whole thing developed much more in the last 30 years and every time I go walking I spend as much time looking down as looking up.
As for books. I have a couple of dozen. Some focus on gathering fungi for the table. Some are more general. I don't really have any which go deeply into things like yeasts and moulds, or their commercial exploitation.
I reckon the 'prettiest' book I have is 'The Illustrated Book of Mushrooms and Fungi', by Dr Mirko Svrcek (as close as I can type it..) I have an edition by Octopus Books, printed in Czechoslovakia. 1988. ISBN: 0 7064 38272 It is full of wonderful illustrations.. I'm guessing watercolours, and features many very rare species.
However, the most useful would be 'Mushrooms and other fungi of Britain & Europe', by Roger Phillips. 1981. ISBN 0 330 26441 9 This one is full of photographs, which make identification a little more certain.. though identification is still potentially a minefield.
Finally, I have a 'King Penguin' book somewhere, covering the major edible fungi in the UK and dating back to WW2. Lovely illustrations and some interesting cooking tips.
The big issue with fungi is that identification of a particular species can be difficult even for experts (which does not include me), and this is compounded by their extremely complex and ever changing Taxonomy. I have books which have entirely different names for what is clearly the same species. Also, the edibility of some species previously regarded as safe.. has been revised over the years, such that for e.g, Gyromitra species, along with some Paxillus species, the advice is now that they are not edible, likely poisonous and possibly deadly.
Let's be careful out there!!
Edit: It is easy to purchase the means to grow Oyster Mushrooms (Pleurotis Ostreatus), and 'Chinese Mushrooms' Shiitake. 'Shii' I believe translates as 'Oak', and 'Take', as 'Mushroom'.
You need fresh logs of suitable trees.. fresh so that they have not had time to be contaminated with other fungi. You buy little 'dowels' impregnated with the mycelium of the 'shrooms' you want. You drill your logs and tap in the dowels as per instructions. Then wrap the logs in plastic until they become covered in mycelium and stick them somewhere sheltered outside. Then you wait..
I grew some Oyster's this way.
The Shiitake were less successful.