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Rod Tulloss said:
The rodent cage odor (“old mouse nest” in my past thinking) is a good indicator for one of the basal amanitas of sect. Limacella, subsect. Vittadiniae. There are several of these in North America, all are rather limited in terms of [known] geographic distribution. They make up a very interesting group. Look up “vittadinii” on the Amanita Studies web site, and you will find a bit of information on the way the subsection Vittadiniae is broken up into smaller groups called stirpes (singular, stirps). A little exploration among these stirpes will lead to finding taxa with “old mouse nest” odor, such as A. nauseosa (which is NOT the species depicted by Alan in this observation).
By the way, amanitas do not have pleurocystidia or cheilocystidia. Their mode of development actually would seem to prohibit the latter because the gill edge is occupied with a cable-like structure that runs its entire length and that gives rise to a long cluster of inflated cells that die and break apart in order to allow the stipe or annulus to break free of the gille edge—there is no room for cystidia on the gill edge.

Lack of a basal bulb on the stipe is common in subsect. Vittadinii (as well as in sects. Amidella, Caesareae, and Vaginatae). Remember “bulb” is NOT EQUAL to “volva.” In Amanita the bulb is comprised of stipe and/or primordial tissues, NOT volval tissue. There are very good views of the volval warts on the pileus in two of the photographs.

Since Alan gives photographs of the spores and since I’m reasonably convinced that this is an Amanita, I thought I’d take a look at what my draft keys would say about determination.
I see several spores in Alan’s photographs that appear to have length/width ratio (Q) of 1.5 or greater; at least one surely exceeds Q=1.6. So, for the sake of argument, assume the average Q exceeds 1.5. In addition we apparently have a narrow ring on the stem. The species is not one with a great deal of volva distributed over the stem below the partial veil.
It seems reasonable to eliminate all stirpes except the largest—stirps Vittadinii. Within this stirps, the relatively narrow spores suggest at least A. prairiicola (=malheurensis). The spores of A. pruittii [provisional name] (Arora’s anonymous amanita) have average Q between extremes of 1.17 and 1.35 (if I remember correctly); so I wouldn’t look at pruittii first. Too many assumptions here to have certainty, but Alan might check further on A. prairiicola as a possible determination. Alan, if you’d like an updated PDF of my description (full macro and micro) of prairiicola that appeared in the Kansas Mycolog a couple of years back, just ask.
Very best,
Rod