Shrooms are organic and leave the system in a few days. LSD is stored in fatty tissue (for many, many years) and is gradually released over time as the fat is broken down -- causing flashbacks.

And yes, I too have found that after you've tripped a while you can train your mind to see the things the other way and force/create a flashbacklike experience
OR Freebird Reviewed by OR Freebird on . Mushroom Flashbacks Has anyone here ever experienced a mushroom flashback? I'm pretty sure they dont exist, but if anyone has had one pray tell. Rating: 5