Hell yeah it will get you high. Though i would be pissed your man diddnt give you any caps.
But to answer your question yes if they are REAL psilocybin stems then you will definitely feel them.
I remember reading the abstract of a Japanese study a few years ago that found the caps to contain around 30% more of the desired alkaloids than the stems. I can't remember all of the species they tested but they definitely used cubensis.