I've always had stomach problems. I had my gall bladder taken out last year, and I suffer from near constant nausea. Cannabis does wonders for me in that department.
I puke almost every time I eat shrooms, if I drink mushroom tea I don't get sick, but chewing them nearly always involves puking later. Recently I ate mushrroms after fasting for a day and puked up an entire toilet full of black shit during the trip. The black shit was a deeply felt and understood metaphor in the way the darkness was voided from me, and the trip kicked into hyper speed afterward.
Mescaline made me puke my guts out about 2 1/2 hours after I ate it, only then did the trip even start. It didn't stop for a day and a half though.
I've never puked on acid, but I have gotten the shits after eating paper acid a couple times.