Buy RS3 Gout tuber
The gout tuber is a rare seed in RuneScape 3. Players plant it in a herb patch to grow goutweed. You need Farming level 29 to plant it. The crop grows in 1 hour and 20 minutes. Planting gives 105 Farming XP, and each harvest gives 45 XP. The patch gives at least 3 goutweed, and better compost can raise that number.
Goutweed has a special use. After the Eadgar's Ruse quest, you can trade it to Sanfew in Taverley. He swaps each goutweed for a random herb at a 1:1 rate. This makes the tuber a handy item for herb stock.
The tuber has other uses too. You can eat it to heal 400 life points and restore all of your run energy. Safta Doc also needs one to make a gem-bladed machete. Getting that machete completes the That's Not a Knife achievement in the medium Karamja set.
Gout tubers are hard to find in game. They mostly come from the Tai Bwo Wannai Cleanup minigame, where a plant has only a 1% chance to appear. Buying one saves a lot of time.