Tricholoma Guide

I just got the new field guide to Tricholomas of North America! I would have to say that this has been my third hardest species to learn. A lot of them have the same macroscopic features at first look. #1 on my list would have to be the Boletes and in second place the Lactarius. I have several books on both the latter ones and still don't know them( except for the prime edibles) and often have to reference the guides. WOOT!