wtf!? I would just confront my parent if they were smokin weed, it's not that hard of a conclusion to come to. Don't be an idiot about it either, you got her red handed. I would suggest asking when she first started smoking, don't act all dissapointed in her otherwise she may lie, but if she started at like 16 then I would eventually tell her you do to. I may be wrong though, I don't know your mom and she might just be a big hypocrite.... but... she is a MOTHER! Naturally she would want to look out for you, so I would take that into consideration. If you do tell her, don't tell her now. Act as responsible as you can and get good grades and shit, then eventually drop the bomb. Only at the most opprotune moment though...