Quick Google-Fu:
"Starting around February, those 21 and older can apply to the Missouri Department of Health and Senior Services for a home cultivation card. A license costs $100.
“They can do six flowering plants, six non-flowering plants over 14 inches tall, and 6 non-flowering plants under 14 inches tall.” For a total of 18 plants, and you can’t go over that at any time. Also, whatever you grow can’t be seen by the public. “So, if you can picture a tall privacy fence that somebody couldn’t look over that was secured and locked, you could have an outdoor patient cultivation under those circumstances.”
You also can’t share your grow with anyone whose name isn’t on the license. Not even if you live with them."
In Ma they can't clearly define "public view". Some lawyers have stated the state's definition is so vague, you could be fined/arrested if a plant is visible from the second floor of a neighboring house. Also in Ma, your own yard is a "public space" if it's not fenced and locked with a no trespassing sign.
Good luck!