early spring is usually the ticket around here, if you go up spring trout fishing, the woods are full of the "mushroom" people!
they have festivals in the small towns in the areas that hold the best hunting and they stress what you mentioned about going with a experienced person first few times and when in doubt, throw out!!
my friend who's been at it for awhile say's he alway's eat's just a few of a "new" mushroom to him because  some people can have bad reactions to even "edible" mushrooms??
my main concern was that some people think buying a book is all you need to do(the do it yourself craze).
and while i'm all for that concept, in the case of something that could kill you or cause major problems, i would feel better having a book AND a experienced guide the first few times ;) ;).