using System;

using System.Collections.Generic;

using System.Linq;

using Newtonsoft.Json.Linq;

​

public class Program

{

    public static void Main()

    {

        string json = @"

            {

              ""items"": {

                ""primary"": ""structured"",

                ""item0"": {

                  ""keyA1"": ""value1"",

                  ""keyA2"": ""value2"",

                  ""keyA3"": ""value3""

                },

                ""item1"": {

                  ""keyB1"": ""value1"",

                  ""keyB2"": ""value2"",

                  ""keyB3"": ""value3""

                },

                ""item2"": {

                  ""keyC1"": ""value1"",

                  ""keyC2"": ""value2"",

                  ""keyC3"": ""value3""

                }

              }

            }";

        var items = JObject.Parse(json)["items"]

            .Children<JProperty>()

            .Where(jp => jp.Name.StartsWith("item"))

            .Select(jp => (JObject)jp.Value)

            .ToList();

        foreach (var item in items)

        {

            foreach (var kvp in item)

            {

                Console.WriteLine(kvp.Key + ": " + kvp.Value);

            }

            Console.WriteLine();

        }

    }

}