Attached is a flower generator using vanilla bone meal on grass in a fairly heavily modded environment. None of these storage drawers are upgraded, and yet corn has filled up THREE WHOLE SLOTS in the test bed while the rest of the slots are fairly evenly scattered about. The next highest in the grouping is dandelions at 5 stacks. That's close to 5 times as common as dandelion, just from bone meal.

I've used the following CraftTweaker insert to reduce the amount of corn dropping for my instance:
vanilla.seeds.removeSeed(<machinemod:cornseed>);
vanilla.seeds.addSeed(<machinemod:cornseed> % 2);