When it's being picturesque, Rhodotus palmatus is a stunning and unmistakeable mushroom--or so they tell me. I wouldn't know, since I only find it looking as though it has a droopy, slimy hangover. In its oft-photographed state the cap features an elaborate network of ridges and veins--but Rhodotus palmatus can also be found (more commonly, if my experience is indicative) without these ridges, at which point identification is more challenging: look for the thick and rubbery cap, the dull orangish color, the pinkish spore print, and the habitat on well decayed, wet wood in stream beds from the Great Plains eastward. Mushroom Expert
Photo source: Another Mag
See also:
Mushroom Encyclopedia - Blue mushroom (Entoloma hochstetteri) #1