Cover beans with water and 1 ts salt, soak overnight. Drain, refill pot with water to cover beans, bring to boil and simmer till soft. Drain. In crockpot, mix beans and butter. Mix together sugar, salt, mustard. Sprinkle on beans. Stir molasses and sour cream together, pour over beans and mix all together. Cover and cook in crockpot on low for 4 to 6 hours.