[Zircom]

It's more or less impossible to know the psilocybin content of any one specific mushroom offhand, and it can vary greatly even between mushrooms from the same batch, thus microdosing with actual shrooms is an inexact science. You can grind them up into powder and mix it together to average it out, but the total psilocybin will still be an estimate at best.

There is 4 aco dmt, which is supposedly gets converted to psilocin just like psilocybin and I don't believe is illegal in the US, however it degrades very easily into psilocin if stored incorrectly so can be dicey to have since psilocin itself is still illegal.