From: Rabbi Moshe Sofer
To: Rabbi Kashman
Wheat harvested for matzah was found softened after heating in storage due to moist stalks. The Chasam Sofer permits the wheat since no actual cracking was found, recommending the pious seek shmurah wheat. He identifies maror as lettuce but recommends horseradish to avoid insect concerns, and identifies karpas as celery.
Source: Shu"t Chasam Sofer OC §132