Mullet are delicious when taken from clean waters (oceanfront piers and cleaner harbors), but otherwise you really want to stay away from those congregating around river mouths or back bays. They feed on detritus, and often pick up toxins and pathogens from human waste. As for catching them, there is an older thread dedicated to this topic. I for one have not found a way to catch them, and many others note the same thing. So far suggestions have been fishing with doughballs, peas, moss, bread, and small, very quickly retrieved bucktails and spinners. If you just wanted to get your hands on a mullet I suppose you could try snagging, but that is rather unsporting and potentially dangerous.