I remember reading about the experiences of a reddit user who documented his microdosing for a year or so. Basically he concluded at the end that it was probably placebo, although it is very hard to say for sure because he was the one recording the effects.

I'll put a link up here if I can find it again...

EDIT:
Turns out it was LSD, not psilocybin.
http://www.gwern.net/LSD%20microdosing

I have been micro-dosing with LSD & Psilocybin cubensis 3-4 days per week for 4 months now & it has had an over-all positive effect on my life, at least from my subjective viewpoint. Giving me enough energy to get through long days of intense physical labor on our new farm while offering the added bonus of more-than-the-usual amount of creative problem solving.

As for DMT journeys while micro-dosing...

My experience has been rather profound in these regards. Some of the strongest, deepest, most intense hyperspatial journeys I have undertaken to date have been on days when I had been micro-dosing all day & then had hit the DMT pipe later that night.

Some of these experiences have been in "the most beautiful" category & some have been in "the most horrific" category, however there was an underlying intensity to all of them that I just could not ignore.

I can only recommend trying this to experienced psychonauts, although I have to admit, almost everything I do I can only recommend to experienced psychonauts. LOL!

I was talking to a woman that was interested in doing something like this. Some article about the LSD micro-dosing experiment piqued her interest but accessing the LSD is something she doesn't want to get into and it is a chemical unlike the fungus. Even when I heard about this I was dubious because of the tolerance issues.

I too was originally leery regarding the whole tolerance thing...

However, it seems that psycholytic doses differ in more ways than we previously thought from psychedelic dosages...

From my experience, I have found no significant tolerance issues of any kind with micro-dosing several times per week, often times 3 days in a row for months on end.

Got up, had some toast, broke up 69mg of panaeolus cambodginiensis mushrooms, juiced a lime, added some hot water and drank it. Ate an apple to keep digestion flowing. About an hour later I feel like I've had a gram of cubensis, lemon tek'd.

I'm quite experienced with mushrooms and I know these old familiar feeling of a cool electrical background buzz in my head and body, grinning for no reason, watery eyes and the strange feeling of cool air in my throat. Could all that just be a placebo or are these really that strong ?