One of my pastures is being taken over by a type of grass that grows in clumps about a foot across. The grass looks like a thin knitting needle, about two feet high with a pointed tip. There are frequently small seeds or something growing near the top of the stem. The sheep won't eat it so I have to go out and mow it down to keep it from taking over. I've googled around but can't identify it; does anyone know what it is?

We live in Maryland, north of Baltimore and about three miles inland from
Chesapeake Bay. I think I used to see similar grass when I lived in Ohio, but I can't be sure, it was a long time ago.

Paul