1) I got a load of what was supposed to be composted mushroom soil.
It's light and airy, but deeper in the pile it smells real bad.
(anaerobic composting?)

2) I planted a few flowers using most all the mushroom soil to replace
the very heavy clay I dug out.

3) After a couple months, most of these plants are dead or dieing.

So..........

Was I wrong to use almost 100% mushroom soil and the nitrogen is burning
the roots?

Is the soil not true mushroom soil and isn't finished decomposing?
Again too much nitrogen?

Note: I have not had a single stray mushroom grow out of the pile of
soil (about 5' round and 3' tall).

Other?