How can I add a new item to my enum list in the inspector?

How can I add a new item to my enum list in the inspector?

I have a list of enums. I want to add a new item to it without scripting to make them more easily modifiable for game designers.
I made an inventory system and I want to define the type of an item. For an example apple is a type of food and stone is a type of object.
Is there a way to group these items in the inspector?
using UnityEngine;
using System.Collections;

public class NewBehaviourScript : MonoBehaviour {
    public const string[] typesStrings = {"Player", "Prop", "Enemy"};
    [System.Serializable]
    public class TypeList
    {
        public enum types
        {
            PLAYER = 0,
            PROP = 1,
            ENEMY = 2
        }

    };

    // MonoBehaviour class
    public TypeList.types selectedType;

    public void Start()
    {
        string selected = TypeList.typesStrings[(int)selectedType];
    }
}

This, however, gives me the following error:

Assets/grouping.cs(5,31): error CS0134: A constant grouping.typesStrings' of reference typestring[]' can only be initialized with null

Solutions/Answers:

Answer 1:

you can use System.Serializable

using UnityEngine;
using System.Collections;
public class grouping: MonoBehaviour {
    [System.Serializable]
    public class class1{
    public enum myEnum {one,two,three};
    public myEnum[] row;
    public string name;
    public int price;
    }
    public class1[] array;
}

useful link 1 for more information:

make your lists functional with ReorderableList

enter image description here

useful link 2
Custom Editors in Unity3D – Part 8: CustomEditor

enter image description here

Unity Editor: Enum Flags as Toggle Buttons
useful link 3
enter image description here

References