Would it be possible to add the possible drops of each crop to NEI integration (configurable)? Additionally, configurable but disabled by default, the tier of the plant in NEI.
That depends on the Crop. It is not just a Recipe saved inside the Crop itself. You can specify a Crop to drop anything you want without having to do chance based Recipes. It usually takes a Random generator, generates a Number between 0 and 7 and decides which drop to drop (In case of Crops with multiple drops)
