The medical marijuana movement is the strongest it's ever been, with successful decriminalization in several states and strong progress in dozens of others.

With these changes has come greater public awareness of just how huge the medical marijuana business really is. In fact, it's so big that if the crop were grouped with other big-time agribusinesses, it would easily be the most valuable cash crop in the country -- worth more than corn and wheat combined.

With the cultivation and ongoing decriminalization of pot come new -- and legal! -- ways to invest in the trend.

But before you try to cash in on the ultimate cash crop, there are a few things you need to know.