Two years ago nobody was selling kale buds at farmers' markets, but last year, all of a sudden, they were everywhere. They're the tasty, colorful, early yellow flowers of the kale plant. The upper parts of the stems are nice and tender, but the lower parts can be tough and chewy.
Kale buds are a perfect example of an edible part of a plant that folks got in the habit of throwing away, or composting. Then some farmer got the idea to bring them to a market and see if anyone would buy them.They were successful enough that, before long, everyone was selling them.