Whether it's a time-limited quest, or just a huge order for Liang, sometimes you need to gather a lot of Jade Clovers at once, and none of them are showing up in the Sea Trading Market. Fear not, adventurer! Here are the easiest ways to get Jade Clovers.
The place with the fastest adventuring time for Jade Clovers is obviously the Gateway of Luck. However, the odds of actually coming back with a clover are pretty low - only 10% per character, UNLESS you happen to have Leif and/or Konley. Leif has a 47% chance of coming back with them, so added to the 10% from one other character, you're at least beating 50-50 odds. Put Leif and Konley together, and you'll get about a 64% shot - the best I've found anywhere.
You might also want to send some folks to the Butterfly Oracle. Now, the Oracle has a one-hour adventuring time, and a much lower shot (if you use Rafael and any five other explorers, your chances are still only about 30%), but that means on average you'll get about one every three hours or so, so it's hardly a waste of time.
If you have a longer timeline, you can also bring back Jade Clovers from the Flower Tower (best combo is Rafael + any three others, for a roughly 42% chance) and the Dragon's Clutch (best adventurer to use is either Rafael or Bluebelle, who each have about a 40% shot). The plus to sending Bluebelle here is that it's also the best combo in the game for finding Silver Wire, hands down.
Did you know that you can find complete tables for the percentage chances of each explorer finding each item on the page for the Place of Legend in question? Head over to this list of available pages, and check it out for yourself!