Laura said:(L) If psilocybin mushrooms are not producing spiritual experiences, what do they do?
A: They bind to neuroreceptors and block certain intense ego oriented thinking. This has the effect of allowing a mass of impressions coming to and through the sensorium to be apprehended. The effect is to make the individual less controlling in their thinking. These effects can be lasting.
Q: (Artemis) So it like dissolves boundaries in a way?
I think the expression "block certain ego oriented thinking" has been already termed as ego death. There is a researcher of ego death, whom I was following for many years on his Yahoo group https://groups.yahoo.com/neo/groups/egodeath/info. His name is Michael Hoffmann. He came with a comprehensive entheogen theory of religion: http://www.egodeath.com/EntheogenTheoryOfReligion.htm
The Entheogen Theory of Religion and Ego Death explains what is revealed in religious revelation and in enlightenment, including the nature of personal control agency.
The essence and origin of religion is the use of visionary plants to routinely trigger the intense mystic altered state, producing loose binding of cognitive associations. This loose cognitive binding then produces an experience of being controlled by frozen block-universe determinism with a single, pre-existing, ever-existing future.
Experiencing this model of control and time initially destabilizes self-control power, and amounts to the death of the self that was conceived of as an autonomous control-agent. Self-control stability is restored upon transforming one's mental model to take into account the dependence of personal control on a hidden, separate thought-source, such as Necessity or a divine level that transcends Necessity.
Myth describes this mystic-state experiential insight and transformation. Religious initiation teaches and causes this transformation of the self considered as a control-agent, through a series of visionary-plant sessions, interspersed with study of perennial philosophy. Most modern-era religion has been a distortion of this standard initiation system, reducing these concepts to a weak interpretation that is based in the ordinary state of consciousness.
His web site with a lot more resources: http://egodeath.com/