For people like me, linq addicts, and based on svick's answer, here a linq approach:
using System.Linq;
//...
//make it linq iterable.
var obj_linq = Response.Cast<KeyValuePair<string, JToken>>();
Now you can make linq expressions like:
JToken x = obj_linq
.Where( d => d.Key == "my_key")
.Select(v => v)
.FirstOrDefault()
.Value;
string y = ((JValue)x).Value;
Or just:
var y = obj_linq
.Where(d => d.Key == "my_key")
.Select(v => ((JValue)v.Value).Value)
.FirstOrDefault();
Or this one to iterate over all data:
obj_linq.ToList().ForEach( x => { do stuff } );