mud stain(n = noun.attribute) - a stain produced by mud;
is a kind of discoloration, discolouration, stain

drag through the mud, drilling mud, gram stain, gram's stain, mud, mud bath, mud brick, mud cat, mud crab, mud dauber, mud digger, mud flat, mud hen, mud midget, mud pie, mud plantain, mud puddle, mud puppy, mud turtle, oil stain, port-wine stain, sea mud, stain