Entryway Landscaping

I'm finally getting started on the landscaping for the farm entryway.

This is the before picture.  When we had the columns rebuilt, we discovered landscaping timbers, long buried, from the original owners landscaping 30 years ago (you can see the straight line in front of the columns).  Tom pulled those out, then dug out all the weeds so I had a clear area to work with.

I used 8x12x2 concrete blocks to edge the area that I'm going to fill with plants.  Hopefully, this will keep the grass from encroaching too much into the planting area.

I'm going to fill it mostly with an ornamental grass and could use some suggestions.  I just need one kind of grass - one that looks feathery and soft and grows about two feet tall.  I thought I had it figured out and was going to use Mexican Feather Grass, but apparently, that can be invasive because it reseeds itself.  Livestock doesn't eat it, so I can't have a grass like that reseed itself onto our pastures.  I need something that will grow in clumps, but not be invasive.

Any ideas?