Difficult situation, I think my neighbors are growing pot?

Recently, we recently had a new couple move into our neighborhood. Soon after they moved in, my lawnmower went missing. I didn't actually see them take it, but they drive an SUV with those oversized chrome rims and I always hear rapper music coming from the radio, so I am guessing they may be drug dealers or something. Well, yesterday when they were gone, I went over to their house and was looking around for my lawnmower and I saw a pot plant in one of those terra cotta flower pots when I looked through their bedroom window. Can I call the cops on them and remain anonymous or will the cops put my name on the police report?