it's kinda quick but also kinda slow lol.

slow but steady method to make gold:
go to world map -> viridian meadow -> fungus grove -> explore the area.
whenever an enemy pops up, hit retreat. if 'inspect the area' comes up, click it.
you will either come across a mysterious mushroom or a chest. both are safe to open or pick up- the mushrooms will always be fairy mushrooms and the chests will always be full of 200-400 gold. best to have a higher levelled party, you'll be able to retreat from all enemies if you're not in the mood to level.

written myself. if you'd like to, paste it on your profile!

I would like to add that if you're a newer player, this is an EXTREMELY effective method of getting gold and pretty much the most effective when you're a new player (though I always used Trollsblight Caverns instead of Fungus Grove). Once you unlock the Lost Grove you'll pretty much never bother with Trollsblight Caverns/Fungus Grove again

You need at least a level 13 team to farm Trollsblight for gold, this ensures that you never end up getting pulled into battle when you hit skip