Not sure we have ever had grass fed beef, if we have we never noticed metallic flavor.
We have tasted it in buffalo meat though, not a fan of it, there is a local ranch here and have tried it a few times.
Cilantro is a favorite around here though, the freshest smelling herb ever. Like a fresh sliced cucumber, yep.
I also like the smell of freshly cut grass so it could be a character flaw?