You can come accompany us to the park, or you could come along to the park. Both are correct. To accompany tends to be more formal. The lady would accompany me to the ball, she would not just come along as its the sort of thing you need to be invited to. She might come along to a party if I told her where one was, but if I asked her to accompany me to a party it would make the party sound a bit formal and dull. You would accompany a police officer to the station if he requested it, as hes politely threatening that you are about to get arrested. Vegetables accompany meat on the plate. Meat never accompanies vegetables, as the meat is the more important.