Combine the egg, mustard, mayonnaise, chives and salt in bowl. Lightly butter one side of each bread slice. Divide and spread the egg salad on three of those bread slices. Top the egg salad with the salad greens. Set a slice of ham on each sandwich. Set on remaining bread slices, buttered side down. Wrap and refrigerate sandwiches at least an hour before serving. When ready to serve, trim away crusts, if desired, and cut each sandwich into quarters.