yeah, sounds like you're talking about trapezius muscles...the two hunks of meat on either side of the base of your neck.
front raises work the traps a little. wide grip standing rows also hit them, as do shrugs (obviously), and deadlifts.
also, it's very easy to let traps take up a lot of the load on lateral raises. you want to rotate the pinky up so it's above your thumb at the top of a lateral raise, and the 'top' of the movement shouldn't go much above your shoulders, as beyond that is when the traps totally take over. going to heavy on lateral raises will pull in the traps. lower weight, and focus on the shoulder joint as being a hinge...and don't let the shoulder raise up at all.