After reaching a mining level of 575 in the World of Warcraft game, you can now start to Trillium farming.
The two maps from Mist of Pandaria, Dread Wastes and Kun-Lai Summit are the two best places for Trillium farming. Dread Wastes is accessible through the Gao-Ran Battlefront in Townlong Steppes regardless of whether you are from the Horde or Alliance in the game. This area has numerous mineral veins but has a bigger territory, plus you have a lot of monsters to kill while searching.
Alternatively, Kun-Lai Summit has a smaller area but has a lot of caves to go into. This place can be reached by taking a boat through the Ancient Passage in the Veiled Stair zone. The boat will lead them to Binan Village which lies southeast of the Kun-Lai Summit for a good session of Trillium farming session.
Below is the map of Dread Wastes and the prescribed route.
Below is the map of Kun-Lai Summit and the prescribed route.