To find the structures in a region, you should, assuming that you are playing the 1850 Campaign ;
-Look at 1850GRC_Cities,inc in VGN/includes folder
-Look for EDO (CTRL+F) region.
-You will find ;
ChgResSites = $merCereals|1
DiscoverResSites = $merCereals|1
ChgResSites = $merRice|6
DiscoverResSites = $merRice|3
ChgResSites = $merFish|3
DiscoverResSites = $merFish|3
ChgResSites = $merSilk|1
DiscoverResSites = $merSilk|1
So the region ressources at start are 1 cereal, 3 rice, 3 fish and 1 silk and you should get random event messages for 3 rice ressources.
If you get a message regarding Silk in Edo although you already have one discovered, I will investigate more.