Grouping menu items + collapse

Hello.

I am trying to group tables under my main menu. I would like some way of collapsing these tables so it's just the group name that shows up. I was just wondering if someone could point me in the right direction on how I might do this. Ideally, I would have a group name and icon that someone could click on and the group expands to show all the entries. Just to clarify, I'm talking about the menu that appears in the main page (not the top or left bar).

Thanks,

Joe