Store multiple inherited classes and keep their custom variable stored

I would like to do a list like :

List<Item> items = new List<Item>();

With all differents types of items that inherit from the main “ITEM” class

potion : item
food : item
material : item

Each class has it’s own parameters and properties like potion has fillAmount etc… that are set to a random number each time to scene starts.

void Start(){
     Potion p = gameObject.AddComponent<Potion>();
     p.fillAmount = Random.Range(5, 50);

What I’ve seen is that if get an Item back like :

if(item[0] is potion){

But this returns zero, any help?
Can’t this list store custom child class parameters?

Are you missing a “s” in “item” name? List is items and not item.
I think you can compare just the types in this specific case.

if(items[0].GetType() == typeof(potion))

Dont forget to populate the list anyway.