As mentioned, you can call in and not give any of your info. However, IF the area where you heard the guy/believe them to be growing it is NOT visible from outside the fence, further info or a warrant would be needed. As Adam said, authorities would not be able to get anything based on a tip.
Bottom line, you would have to be involved to some extent. Tough call being your mother lives right next door and you could look at it both ways.
Not next store but behind, he's actually on my uncles street which is directly behind me. I don't know for sure what's going on. It's really all about what I heard him say, I realize words could mean little to nothing sometimes. I don't know what to think at this point.