Mississippi does not have any legalized marijuana policies in the state. This includes for medical use. The state laws maintain criminalization of the drug. This follows federal law. While many states have legalized marijuana at least for medical use, the federal law still maintains that it is an illegal drug and imposes federal penalties for its possession, distribution and use. Knowing federal law is important because federal law takes precedence on any federal land, which includes parks and national monuments. 

NORML explains that federal marijuana laws make it illegal to posses any amount of marijuana. You could go to jail for having any amount on you for up to one year for a first offense. Growing any plants also is against federal law and could put you in jail for up to five years on a first offense. 

The federal laws also ban selling paraphernalia. This is anything you would use to smoke the drug, such as pipes or rolling papers. Selling marijuana paraphernalia could mean up to three years in jail. 

Do note that except for the possession of marijuana for a first or second offense, that these charges are all felonies. Furthermore, the federal law also uses mandatory minimum sentences for drug possession starting on the second offense. 

Selling marijuana could also lead to the death penalty at the federal level. The law says if you grow it or sell it as part of a criminal organization, it is a capital crime. There are restrictions on the application of this law, but knowing this helps to explain the federal stance on marijuana.