Dandelions are a Vanilla item that can be be found on Grass or by using Bonemeal on a Grass Block to grow them. They are more common than Roses. Dandelions can be used to make Dandelion Yellow Dye and for crafting the Harvest Goddess Band.
The Dandelion can also be used in Cross Breeding. Holding 4 Dandelions at once and right-clicking on a Crop will plant all 4 Dandelions.
In Cross Breeding, Dandelions are considered a Tier 2 Plant (Tiers range from 1-8).
When Dandelion Crops are harvested, there is a chance for it to drop Dandelion Yellow and/or a Dandelion Seed Bag.
Dandelion Growth Stages: