I would say NIDA provides the pot for research. You would most likely have to contact HHS and get a permit and then the marijauna from NIDA. You would also have to be a legitimate research organization or university that does medical and scientific research. Not "Bill and Ted" looking for an 'excellent adventure'.

I think the University of Mississippi grows the pot for NIDA. Other universities want to start growing their own.

There is no major legitimate medical organization that advocates medical marijuana. How could they? They expend a lot of effort trying to get people from smoking cigarettes. They would look like fools telling sick people it would be alright to smoke something else. Especially a substance that is smoked without a filter, and which is inhaled much more deeply then cigarettes. A substance which also raises blood pressure and causes the heart to race faster.

Some research also shows that pot is damaging to the lungs.

Why would any legitimate medical professional tell sick people to smoke something when they can get the active chemicals in a pill form?