Lean to identify by growing in backyard, from know spores
The more you know an item the easier it is to identify an impostor. Therefore if you grow your own mushrooms and eat them often it will be more easy to identify those particular species in the wild and avoid any that may have toxins. Same with plants where you could easily get confused if you were very hungry, low light conditions and had not "read the book" on them in a long time.
Most arborists (tree trimmers) have a bunch of cut logs they are happy to let you have, just ask them for the tree species you want, or hear chainsaws and chippers and drive over and ask for some. Then grow your own shiitake or whatever native species you prefer, in straw or wood chips or whatever. Join a local club to learn more, go on a guided tour with someone who knows a lot, or just read up and watch a bunch of videos. Here is a quick little intro video:
http://youtu.be/yGWjZXDstbc
Personally I will not eat a mushroom or plant unless I am absolutely certain. I don't trust grocery stores and restaurants either if there is something that looks strange mixed in I will ask, and if the answer is off I don't eat it.
sorry if my comments were misleading
hunter63 I appreciate your additional remarks. I was just suggesting that videos like that one I linked are only an introduction, growing mushroom as with most gardening is mostly for people primarily looking for fun and recreation etc. not cost effective sustenance. (I am a Certified Master Gardener and have taught many classes and spend many hours on county's hot line aswering questions etc. after growing acres of darn expensive food.) Also I stated "Shiitake OR native", never said they were native, and many mushrooms native to certain parts of country or parts of forest but will not grow a few yard away in a sightly different micro climate. Can be very frustrating. Also not all have the same nutritional value but many are generally fairly high in carbohydrates and protein by weight compared to many of other wild forage foods.