I have started eating salads again! Farmer's market is open. Anyways, these salads greens are mesclun, "flat leaf" kale and spinach (which looks nothing like store bought / salad bar spinach). Anyways, I'm noticing there's a distinct "gritty" feel with some of them. Haven't quite narrowed it down, and it's not consistent. Naturally, I wash them before use and I don't see any kind of particular matter on the leaf surface, so I assume it's something inside some of the leaves.