a strange request

My cat likes to run to the end of my apartment building to eat the weeds that grow there. I tried putting some in a planter box outside my door for him, but they died (I don't think I got enough of the roots when I pulled them up).

I think it's crabgrass.

How do I go about getting some of these seeds? I'm assuming they don't stock them at Lowes.....

that's because crabgrass is classified as a weed. How about cat grass or catnip?

I guess I could try that but I have no idea if he'd like it. do they sell catgrass seeds at lowes?