Cantharellus rainierensis is not in index fungorum, and this observation is the only google hit for that name.

off the top of my head. I believe I first heard reference to it by Dr. Eric Danell in a talk he was giving to the North American Truffling Society, detailing his cultivation of C. cibarius and the lack of any C. cibarius in the US. I remember at one time seeing the C. rainierensis was proposed as an endangered species, but collections appear nearly every year in commercial mushroomers, such as Arley Smith of Smith’s Forest Fresh Products. I remember taking photos of a foot-tall C. rainierensis at Arley’s. Observation may be here somewhere. A single mushroom dwarfs C. formosus, and C. cascadensis is relatively rare in my area, but more common in southern Oregon. Typically it is 6-10 inches tall. There are variations in coloration which are difficult to describe, but easy to see when specimens are placed side-by-side. Flesh and stipe thickness are some of the charactistics, but there is slight but noticable variation is coloring as well.

The first books I would check for both species would be Smith, Smith and Weber’s How to Know the Non-Gilled Fungi; and the fungi associated with the Record of Decision for the Northern Spotted Owl. Don’t have actual citations for either book at hand, but I hope you know which ones I’m talking about.

Redhead, S. A., Norvell, L. L. and Danell, E. 1997. Cantharellus formosus and the Pacific Golden Chanterelle harvest in Western North America. Mycotaxon 65: 285-322.

Daniel – Do you have a reference for Cantharellus rainierensis or photos?
Cantharellus cascadensis is also large and found in Oregon.

is apparently not found in North America, from DNA analysis done by Dr. Eric Danell. In fact, C. cibarius is quite rare and has a very limited range in Scandinavia, part of Denmark, and a small piece of England. DNA evidence is surprising most of us.

While it is likely what you collected was C. formosus, which is the most abundant species currently known in the PNW and is Oregon’s state fungus, there is another species which your collection is approaching, at least in size. C. rainierensis is a huge relative, with individual mushrooms reaching 1 pound in size, and often over 8 inches tall. While the type collection was found near Mt. Rainier, it appears to be scattered through much of the Cascades and possibly the coast range as well.