MrJesus, I will tell you the same thing I have said in the past.
You have two choices: 1. Respect your mother's wishes and make the effort to rebuild the damage in your relationship, regain some trust and respect. You can both learn from this and can actually strengthen your bond. You have an opportunity to really become close through the whole " cleaning out the closet" thing you are faced with here. Get her to really know you, and you to get to know her. Your realtionship is moving out of the mommy and child stage and into mutual adult stage and you can use this moment to do it with a closeness that you wouldnt have imagined prior. You also have the opportunity to both educate yourselves on the effects of marijuana in your lives and relationship and for her to shed some of the "reefer madness syndrome" and you to shed some of the "secret stoner syndrome" Once she learns that it is not a "gateway drug" of something that will fry your brain and ruin your life you might find some freedoms to enjoy herb without fear or risk.
Common ground my friend is a wonderful place to stand with your mother. Trust me.

2. Ignore her, try to be stealth and risk further damage to your relationship that may take YEARS to overcome.

Its your choice.
Whatever you decide, do it with the knowledge that each step you take brings you closer to your future.


peace.

FM