using System;

using System.Collections.Generic;

​

public class Item

{

    public string Property { get; set; }

}

​

public class Program

{

    public static void Main()

    {

        var list = new List<Item> { new Item() { Property = "test" } };

        foreach (var item in list)

        {

            item.Property = "updated?";

        }

​

        foreach (var item in list)

        {

            Console.WriteLine(item.Property);

        }

    }

}

​