public class Foo{
        public string Prop1 {get;set;}
        public string Prop2 {get;set;}

        public Foo(Foo source) {
            this.Prop1 = source.Prop1;
            this.Prop2 = source.Prop2;
        }
    }

    public class Main
    {
        private List<Foo> items = new List<Foo>();

        public IEnumerable<Foo> GetItems() {
            foreach (Foo foo in items) {
                yield return new Foo(foo);
            }
        }
    }