Well, its clearly stated to be tobacco in The Hobbit, & I suspect Tolkien only changed it to 'pipeweed' in LotR because calling it tobbaco would have sounded too anachronistic, & caused problems of explantion. Of course, Tolkien does state it was a variety of nicotiana, so he clearly intended it to be similar to tobacco rather than cannabis. I suspect that it tasted very similar to the coffee-caramel flavour tobacco currently available (that's a personal feeling based on what I smoke
And for the record, I'm just a bit older than PJ & I've never touched 'weed'. Tobacco, the real stuff, not the chemically laced junk they put in cigarettes, for all its risks, is very calming in its effects & is most conducive to thinking.