public static readonly List<int> MyList;

//Initialize MyList in the static constructor
static MyObject() { ... }

public static readonly List<int> MyList = GetMyList();

//Returns the list
private static List<int> GetMyList() { ... }

public static readonly List<int> MyList =
    () =>
       {
           ...

           return list;
       };

() =>
   {
       ...

       return list;
   };

Func<List<int>> createList = () => { ... return list; };
MyList = createList();

public static readonly List<int> MyList = new Func<List<int>>(
() =>
{
    // Create your list here
    return new List<int>();
})();

public static readonly List<int> MyList = new Func<List<int>>(() => {
    return new List<int>();
})(); //<-- the parentheses that invoke