Answer: The grass you saw is most likely Korean grass, or Zoysia tenuifolia. More of a ground cover than lawn grass, it's only hardy in USDA Zones 9 through 10. The thick thatch, lumpy growth you describe is very characteristic.
There is a native American grass called buffalo grass, or Buchloe dactyloides. This is a perennial bunching grass hardy to USDA zone 4 and grown in many parts of the nation. It's reasonably care-free, requiring little water or maintenance, and spreads rapidly by surface runners once the plants become established.
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