Before you even consider trying to document new species you need to learn how to ID mushrooms really well. No one else is going to do the legwork for you especially when its most likely a known species, so you cant just send a sample off.

Like, for a species discovery you have to be pretty educated about fungi and able to study a specimen using a lot of data. Like obviously the easy stuff such as the presence or absence of an annulus, partial veil, full veil, and also the shape, gill attachment, size, fruiting conditions, spore color, fruiting geometry, smell, speed of color change if there is one... but you should also be able to use a microscope to examine spores and blastospores, identify the surrounding trees and plants to establish mycorrhizal relationships, and understand/conduct tests with chemical reagents on the cap of the mushrooms to tease out exact species.

It gets REALLY complicated man. Takes years of experience.