Pass Selected Shape to Feature Service?

Hey folks,

Is it possible to select a particular layer from an operational base map and pass that geometry to a feature service? 

For example:

1. I want to have a pick list of County & State (both layers in my operational base map layer) 

2. User picks County and clicks the map, highlighting that County.

3. Geometry of County gets passed to feature service and user continues editing attributes.

Any ideas? Samples? Am I dreaming?

many thanks!

ryan