What weed/grass is this?

[Stephen]

This grass grows very well in my garden. What got my attention to it was that my kittens and older cats love it so much. They chew on it whenever they are outside. I'm thinking of taking the grass to their vet in order for him to have a look at it.

 

[Shortie]

At first glance, I wanted to say it's a dock leaf but after further checking on Google, it seems that it is not a dock leaf.

I would take it to your vet to take a look though!