Custom class list seen as "none" in inspector.

As shown below, i've made all the implementation as far as i know and it seen as none in the inspector when run the game.

 public class item_database : MonoBehaviou![alt text][1]r
 {
     public Sprite[] spriteboxes;
 
 
     public List<item> items;
 
     void Start()
     {
         items = new List<item>();
         set_database();
     }
 
    
 
     void set_database()
     {
         items.Add(new item(item.itemType.food, 0, "carrot", "garden food", spriteboxes[0]));
         items.Add(new item(item.itemType.food, 1, "red mushroom", "wild food",spriteboxes[1]));
         items.Add(new item(item.itemType.food, 2, "mushroom", "wild food", spriteboxes[2]));
 
       
     }
 
 }
 

[1]: /storage/temp/180253-screenshot-3.png