How much jail time would you get if first time offender and caught with 20 lbs of marijuana in Mississippi?

Depends how much you are over the limit, under 30lbs you might get away with just a heavy fine. Normally though, anything above that though you would face above a year in jail or suspended sentence with a community service/fishing curfew. However for both you will be permanently banned from fishing.

Minecraftguy XD