To get Dandelion Seeds in Genshin Impact simply find Dandelion Plants and blast them with an Anemo (Wind) attack.
Map

Here are 5 spots near Mondstadt where you can find and farm Dandelion Seeds.
- On both sides of entrance to Mondstadt. This one’s my fav.
- A small patch of three.
- This area has a bunch but is a bit harder to get to.
- Another small patch.
- Not much here but it’s easy to get to.
Dandelion seeds are a character ascension material for Jean. They can also be used for crafting Gushing Essential Oil (Anemo Dmg) and Windbarrier (Anemo Res) Potions.