The Grass Blockling was originally added in 1.7.2, in the current version you can only upgrade him using Grass Blocks or Dirt Blocks, but they are pretty easy to find since they spawn in any place that has.... well grass!
He's also the weakest, but also the most cheapest Blocklings in the mod and more common out of every Blockling. His main attribute is farming, and also good speed. And we can consider him really easy to tame/find.
In the current version you can only get 1 variant being the Grassy Blockling, but there are plans to add more variants to all Blocklings in the future
Grass Blocklings have a chance to turn any dirt they walk on into grass.