go and do a course first then only if you are 500% sure you can positively identity the mushroom, don't eat anything or you will meet your maker in no time. don't be foolish!.humble advice!
surprisingly there are actually a lot less deadly species of fungi than we think there are. Most of which are just inedible because they are too tough to chew or are just plain indigestible. The rough percentages of the fungi which you will find will be -
50% Inedible
25% Edible (But either are bland/tasteless or just doesn't taste nice at all)
20% Will make you ill (Gastric problems, instant vomiting, stomach cramps e.t.c)
4% Taste great (The ones that we usually go look for!)
1% Deadly (Goodbye)
Although this doesn't seem all too bad, I haven't tried a single fungi that I am not familiar with even though I have seen hundreds out on my travels. This again, is to the risk of the user. If you want to take that risk then it's your decision but all I think is that when I take into account how seriously ill they can make me, let alone kill me I personally don't fancy eating them. I wouldn't worry about turning them away too much......there's very little nutritional value in most fungi anyway so its not really an option to look at as a survival food. Anyways, good foraging and good luck!!!!