culm

olki, korsi waste coal, used as a poor quality fuel; slack.
1887, Homer Greene, Burnham Breaker, Chapter XXI:

Here he lay down on a place soft with culm, to take his contemplated rest, and, before he was aware of it, sleep had descended on him, overpowered him, and bound him fast.

...because, upon hearing him out, she sank down on the lawn in an impossible posture, examining a grass culm and frowning, he had taken his words back at once;...