Building DropDown Lists In MVC

I have an self-referencing entity which maintains a list of like entities that are it's children. What I need to do is build a dropdown that lists all possible parents so when I add or edit a new entity of that type, I can select it's parent (or no parent). The problem lies in the sql. I simply don't know how to word it.

IList<ParentForumModel> parentForums = new List<ParentForumsModel>();
foreach (Forum forum in forumRepository.GetAll())
{
// not sure how to handle this here because it isn't in the correct order. I need them to be grouped by parent and sorted by the sequence field. It also needs to be a flat dataset, not something uses IGroupedQueryable or some such.
}
ForumAddModel model = new ForumAddModel
{
ParentForums = parentForums,
// other properties
}

public IQueryable<Forum> GetAll()
{
return context.Forums.??? // what Linq do I need here?
}

If this simply isn't possible with Linq2Sql, then is there a system where it is possible? Please don't say hnibernate.