Man, if my parents ever grounded me or punished me, I only listened to them if their grounding was justified. Did I sneak out at night and get piss-ass drunk? Then yes, I ought to be punished. But that lighter bit? Thats bullshit. If she is going to punish you for finding a friggen lighter in her house that isn't even yours, then I don't think you should listen or her or respect her decision to punish you.

I have found that the best way to get back at my parents for their anti-weed business was to show them that it doesn't actually fuck up yer life. Be a "success" and prove them wrong.

Unfortunatly, there isn't a whole lot that you can do as of right now. If you have tried to talk with her adult to adult, and she isn't doing the same, then screw her. If she wants to treat you like a fool, then she doesn't deserve your respect.