Homestead Arcana

This can be done as early as the tutorial. Walk into the cloud of Miasma gas and stand in it until your lose all your health and get knocked out. Repeat this nine times for the achievement to pop.

Just be aware you'll lose items in your inventory (including Silver) when knocked out. So best to do this with an empty inventory.

If you don’t want to get knocked out by running out on time on your mask, another quick way is to get attacked by the Hoppers! (Or any of the hostile animals you’ll encounter) First Hopper you’ll encounter is the next section after your Aunt’s house. They will pop up to attack when you enter their radius.

The only items you’ll lose when getting knocked out is the new items you pick up in the miasma. You’ll know what items by seeing the items covered in the purple miasma in your inventory. When you leave the miasma, the items will be safe, and you won’t lose them if you were to get knocked out afterwards.

Honestly I’ve been knocked out plenty of times by trail and error navigating the miasma! You might not get this on purpose!