The Byron Reed example of the popular 1863 Washington obverse design with the "Curved" 2 cents reverse struck in copper-nickel. This piece was originally believed to be oroide but was analyzed and found to be copper-nickel.
Examples were struck in the following combinations.
Copper/Bronze J305/P370 This is one of the more common patterns and is known on both thin 78 grain and thick circa 92 grain planchets.
Copper-nickel J306/P371 with about a half dozen known.
Oroide J307/P372 This may not actually exist as the Byron Reed example is the illustrated example above.
Aluminum J308/P373 with at least 4 specimens known.
Photo from the Byron Reed Collection; owned by the City of Omaha, Nebraska; on loan to The Durham Museum.