I wouldn't use yard grass. I feed mine dried grasses - timothy and orchard grass. There's probably nothing wrong with feeding a little wheat grass, though you might want to check on that.
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Torey
Eugene, Oregon, USA
1.1.5 Saharan Uros (Joe, Arthur, Waddles, Stilts, Hitch, Lefty, and one more)
3.0 Mali Uros (Spike, Turtle, and Tank)
1.1 Ornate Uros (Scuttlebutt and Shazzbot)
2.3 Collared Lizards (Ripcord, unnamed male, Thiamine, Riboflavin, and Niacin)
2.0 Green Anoles (Bowser and Sprocket)
1.1 Chubby Housecats (Roscolux and Jenny)