Sky Blue Flower

Two very different homes. Jungle grass at almost any depth is the obvious one. The other is plain sand sitting under a couple of tiles of liquid near the surface, and that is the version people never find, because you have to be swimming to notice it. They also show up on the minimap as pale blue squares, which helps on a wide sweep.

A pickaxe or drill is the only way to take one. Hitting it with a weapon just destroys the plant. A Spelunker Potion lights them up, so running the jungle with that buff active is by far the fastest way to gather a stack.

Convert the pile at a Dye Vat before selling any of it. The finished dye is worth considerably more than the raw flower, and there is no reason to sell the plant unless you have no vat within reach.