I have a combobox that I populate like this:
this.reqTypeInput.Items.Add(new RequestType(\"Label 1\", \"Value1\"));
this.reqTypeInput.Items.Add(new RequestType(\
Lot's of choices, List, SortedList, Dictionary, SortedDictionary. But basicall you keep your collection of RequestTypes in a list and then populate the combo from it, you could even bind if you wish.
The only thing the combo knopws about your collection of request types, is the result of each RequestType's ToString method. If you want find by Value, then Combox will only see waht you put in it, which was RequestType.ToString()