I know that Double Tallgrass has a particle effect that I think should change color. The color should be green instead of gray. To find this out, go out in a Plains biome (just looks easier, not specifically) and put down a Grass Block. Next to that Grass Block, you should place a Double Tallgrass, but elevated 1 block down. Then, crouch to the end of the Grass Block you placed down and be in front of the Double Tallgrass. Finally, fly up (be in Creative, it's easier) to the point where you can take fall damage, and drop down. When you take fall damage, the particles spread out depending on what block you fall on. Since the Double Tallgrass doesn't have any way to touch it, it wouldn't be considered a block, so the particles change to a gray color instead of something Mojang actually implemented (again, color wise). I also have a screenshot below to show what this particle looks like. The gray you see is the particle for the Double Tallgrass. I was not using any resource pack of any sort (I'm not fond of them), so this is not fake.