Found it. This is from the Ontario Canada Gov't weed site:


Name: Yellow nut sedge, Cyperus esculentus L.,

Other Names: CYPES, souchet comestible, Chufa, Earth almond, Ground almond, Northern nut-grass, Nut-grass, Rushnut, Yellow nut-grass, amande de terre, souchet rampant.

Family: Sedge Family (Cyperaceae)

General Description: Perennial, reproducing by seed and by underground stems (rhizomes) and tubers. It is easily distinguished from all grasses by its triangular stem together with slender, tuber-bearing rhizomes. Several other species of nut sedge also occur in Ontario but this is the most troublesome one and the most likely to occur in cultivated land.