IF you haven't met with your Advisor, principle or whatever yet.. I would like to say i have been in the same situation. When I was in my sophomore year I sold some kid one single joint, the kid got busted with it and ratted me out. The next day they called me down and sat me down in the office with the principle, assistant principle and the school officer which also is a town officer after badgering me and accusing me they searched my bag and found two joints. I ended up being suspended for a whole semester even though i hadn't been in trouble, NOT ONCE for anything but because they scared me into agreeing with them. This F'ed up the rest of high school for me there it caused me to not graduate on time, screwed me on going to college etc. You need to explain to them what a mistake you made and that you know you made this mistake, you are sorry and explain to them the impact it will have on your future I cannot stress enough how much it will throw everything off track by getting suspended or expelled. Think of other alternatives to suspension, offer to take drug class's etc. All i can say is really try man, Good luck.

** let us know how it goes...