For once I'm with Chico. Parents educated about marijuana ((or even ones that aren't who think 'it's just a phase')) will often intentionally play dumb about it. Just fess up like she clearly wants you to and tell her you'll keep it on the minimum like you always have. ((even if you havent.)) Parents aren't stupid. Especially the ones that partied a bit in their youth.

Just make sure you always put away your paraphinalia and weed in a place where your parents will never find em. Also ensure that you always respect their house by either smoking outside or using a spoof and an open window. And don't smoke joints or blunts because obviously their smell is significantly harder to conceal.

And even if your mom is cool with it, don't be a dumbass and be like "Yo mom! I just got a PHAT 1/8th from my dealer for 25 bucks! And this is some dank shit! Wanna smoke a J with me?"

The first time my mom really knew I smoked weed was the day after her sister ((my aunt, they were really close when they were younger)) had died and I was pretty sure she had suspected it for a while.. so I was just like "Want me to roll us a joint and go pick up a funny movie?" and my mom said "Please." She's never smoked with me since, but it was awesome smoking with her. Really bonding style and stuff because it's like you and your parent finally have some common ground. My mom hadn't smoked weed ((even though she used to be a major pothead and alcoholic)) in over twenty years. Needless to say, she got fucked up.