When I was child [in Co. Meath] I was told by an old man in the village that if you stood on the hungry grass, if you had nothing to hand to eat you would be rooted to the spot, and presumably starve, so I always carried a crust in my pocket.
I had a chat with my mother … and she said that it was spoken of across all of Ireland, referred to in Irish as An Fear Gorta (pronounced On Fair Gurtha) [East Sheen, Surrey, April 2012].

Image: quaking grass (Briza media), Bernd Haynold, Wiki Commons.
Hungry grass has sometimes been identified as quaking grass, but it is more probable that it cannot be identified with any particular species (see N. Mac Coitir, Irish Plants, Myths, Legends and Folklore, 2006: 193, and R. Vickery, A Dictionary of Plant-lore, 1995: 199).