Tell her to stop searching your shit because you're 17 years old. I'm 16 and I would be pissed if my parents searched my shit on a regular basis. The only time they searched was when I was caught for the first time.

Anyway a good spot could even be in another room of the house that people don't go in or use that often if you have one. Just find a spot where no one would ever go normally. I'm sure your mom won't be searching for pot in rooms other than your own. Hope I could help.