How to get, grow and ride a Happy Ghast in Minecraft
Its mechanics are unchanged up to 26.3; the only addition is the Golden Dandelion in 26.1, which can keep a baby small.

The Dandelion is a small yellow flower found in plains, forests and most grassy biomes. It is the usual source of yellow dye, and rabbits and bees are fond of it.
It cannot be crafted; it can be found in chests. It can be composted: each one has a 65% chance to add a layer to a Composter.
Crafted on its own, a dandelion gives one Yellow Dye. In a suspicious stew with two mushrooms, it adds a short burst of saturation, which makes that stew more filling than a plain one.
Rabbits trail after anyone carrying dandelions, and two rabbits fed with them produce a baby. Bees pollinate dandelions and carry the pollen back to their hive, helping nearby crops grow on the way. Eight gold nuggets around a dandelion make a Golden Dandelion.
Dandelions grow from bone meal used on grass, fit in a flower pot and go into a composter. They pop off when the block below them is removed and are washed away by flowing water.
This item has no crafting recipe.
Its mechanics are unchanged up to 26.3; the only addition is the Golden Dandelion in 26.1, which can keep a baby small.
Mining the block drops it. It can be found as loot in Village. Sold by Wandering Trader.
It makes yellow dye and a saturation suspicious stew, breeds rabbits and is the base of the golden dandelion. It is an ingredient in 3 recipes, made at the Crafting Table; for example Golden Dandelion, Suspicious Stew and Yellow Dye. Effects: Saturation (Suspicious Stew). Animals that eat it: Bee and Rabbit.
Yes. Each Dandelion put in a Composter has a 65% chance to add a layer (the first layer in an empty Composter always works). After 7 layers the Composter gives Bone Meal.
No: when a piston pushes it, it breaks and drops as an item.
Yes: fire can spread to it and destroy it.