I've taken an eighth of mushrooms and then took 700mg DXM two hours after I took the shrooms, then smoked a few bowls of weed and then a bowl of 10x salvia from a bong. It was fun, I was laying on a couch and I hallucinated I lifted off the ground, flew out the front windows of the house and started flying around the neighborhood.
In reality I was laying in an empty bathtub with all the lights underneath a blanket. It was fun, but the hallucinations (and I do mean hallucinations, not just pretty patterns) were intense.
I would recommend taking just the shrooms, or just the DXM, or just the salvia. The experience of each individually is interesting and the larger dose of whatever you took tends to guide everything anyway.