It seems likely to me that any form of smoking was discovered incidentally by burning stuff that smelled nice, repelled bugs, repelled evil spirits, etc. and happening to inhale some of the smoke.
For mushrooms it was probably desperation, but my head cannon for mushrooms is Trial by Mushroom: You can be expelled from our community for stealing, or you can eat this mushroom and if you survive, you get to stay.
For mushrooms it was probably desperation, but my head cannon for mushrooms is Trial by Mushroom: You can be expelled from our community for stealing, or you can eat this mushroom and if you survive, you get to stay.