This happened to me. As soon as the last piece of mush was down my gullet, I sparked up, thinking I'll apply some anti-nausea gas to my system in preparation for the trip in an hour or so. 3 hits into it I was laughing uncontrollably and as high as the peak of an LSD trip.
Yup... hits me the same way too... I found this one out by accident... I figured a nice chilled weed buzz to start - then have the mushies hit... but nope (together its a whole new buzz). BTW: For anti-nausea.... If you want to beat that easily... try popping a gravol about 20 min before eating your shrooms... works every time