Scrape off as much of the dried-in mud as possible by taking the clothes outside and brushing with your hand.
Mix 2 tbsp. of powdered laundry detergent with enough water to form a thick paste.
Apply the paste to the mud stains. Cover the stains completely with the detergent paste. Leave the paste on the clothes overnight.
Place the clothes in the washer. Set the water temperature to the hottest setting allowed by the clothes manufacturer.
Pour 3 tbsp. of liquid detergent into the washer. Add 1/4 cup of bleach for white clothes or color-safe bleach for colored clothes.
Repeat the entire cleaning process if the stain remains.