Where do I get black sunflower seeds to grow?

I’m trying to set up an area to show kids different types of crops that are grown.
All the seeds needed have been difficult to track down in small enough quantities, but black sunflower seeds that will actually grow are particularly hard to find… if not impossible.
Yes you can buy them for bird seed, and they may or may not grow into the same variety grown commercially, but I need something a little more reliable.
I’m trying to set up an area to show kids different types of crops that are grown.
All the seeds needed have been difficult to track down in small enough quantities, but black sunflower seeds that will actually grow are particularly hard to find… if not impossible.
Yes you can buy them for bird seed, and they may or may not grow into the same variety grown commercially, but I need something a little more reliable.

To be clear, I need a small black seed sunflower type that’s commercially grown.