They work as all crafting furniture do, you get a boost for speed and experience for each unit crafted, depending on how many furniture and for which profession you have added to your house.
So considering the three collecting professions, you only profit from these bonuses while processing goods into higher rarities in your house, not while gathering mats in the open world.
Cheers!
Thanks for clarifying. I've never actually furnished a house in this game but was aware that you get a buff of some sort for XP & TP so I thought you got a similar one for crafting too based on how I read this thread.