Black drum are basically harvesters. They will root around on the bottom looking for food in the grass, sand and mud. They will vacuum up most anything that has meat. From small crabs and small fish to mollusks, worms and shrimp the shallows are a buffet for black drum..
The whiskers, called barbels, near their mouths are used to sense food by both smell and feel. When they are actively feeding, you may see a sandy or muddy cloud moving through the water or even their tails sticking up through the water as they move around with their head churning the bottom.
While plowing up the bottom is their primary feeding pattern, they will be opportunistic by grabbing a small shrimp or fish that gets too close.