Zone 8B South Carolina, looks edible :P
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This is in the sedge family (Cyperaceae) rather than the grass family (Poaceae). Use this helpful mnemonic device for classifying grass-like plants:
Sedges have edges, and rushes are round, But grasses have nodes from their tips to the ground.
If you roll the stem of a grass-like plant between your fingers, it will either feel round and smooth, or it will have edges. Members of the sedge family have a triangular cross-section, and you'll feel the edges of the triangle.
More specifically, my best guess is that it's a bulrush, a member of the genus Scirpus. Dark green bulrush, Scirpus atrovirens, seems like a reasonable possibility. For truly accurate ID, you really have to get into identifying (and sometimes measuring) specific floral parts.
According to the Peterson Field Guides' Edible Wild Plants of Eastern/Central North America by Lee Allen Peterson, Scirpus acutus and S. validus have edible seeds, pollen and rootstocks that can be used as flour. So if it turns out to be one of those two species, then parts of it are edible. But don't eat a plant you haven't positively identified based on multiple characteristics and reliable references.