You could eat it. It's not the greatest tasting tuber, but if you decide you like it then it's sure to fail for some reason. :)

Nut grass is a sedge, so regular grass-specific herbicides don't faze it. Things like Roundup will kill the existing plant, but not the nuts at the tips of the roots which will grow new plants in no time. What you need is sedge killer which will kill sedges like nut grass without harming the grass or ornamental plants it has invaded. Look in the herbicide section of your big-box or farm/garden store. It's an essential weapon for gardeners in this area -- and it's a lot easier than moving to another location where you'll just encounter more nut grass!

Image is the trade name of one pretty good nutgrass killer. Sledgehammer is another. I think that my husband has switched to the latter and it does a very good job.

The little tubers on Yellow nutsedge taste very nice, but the Purple nutsedge is nasty, bitter!

I used Image and it worked good for me.