Found massive amounts of MaryJane in my house. What do I do?.

Long post. Washington State. My partner's(62) son(42) and granddaughter(28) are both drug addicts. They were living in our house and shared a room. Due to a restraining order they no longer live in the house. However, they are to come with the sheriff to pick up their belongings. They are telling police we want to destroy their things and got an order for us not to do so, which was never our intention. We told them we needed to get OUR items out of their shared room and that we would video ourselves doing it so there was no mistaking that we did nothing to theirs. Well, we wish we had never gone into that room because we now believe WE could be in trouble. Opened the door and the smell nearly knocked us over. We knew he smoked it which is legal here so didn't think much more of it. Removed the first item. To get to the other we needed to move a huge Rubbermaid tub with 5 full, 14 gallon trash bags on top of it. To lighten the weight of the tub we began moving the bags when the lid popped off. Boy oh boy! Another 6 bags in the tub, one with the top open. It was filled to the top with the stuff. We were stunned as we looked around the room realizing there were more and more bags... 17 in all. We immediately called the sheriff and told them about it saying they(son & daughter) had no right to bring it into our home and we wanted it out and to come get it. The sheriff's response baffled me when all I got was a "I'll call you back in a few minutes." But he never did. We thought they would want to get this out of my house. How nieve are we! Just a bit ago I googled what to do if you find drugs in your house. The answer's were split with some saying to do what we did, others saying absolutely NOT to because we could be arrested and charged for the drugs instead of the people who actually brought it in. Since we already made the phone call and them not calling back, could they be getting a search warrant so they can legally charge us? Are we going to jail for something other people in the household did?? We are both seniors on limited income and we do not have funds for an attorney. What should we do now?