2,800. What Is Considered Produce of the Earth?

Hilchos Nedarim 9:10

If someone vows not to eat vegetables, he may still eat squash. If he vows not to eat leeks, he may still eat scallions. If he vows not to eat cabbage, he is also prohibited water cooked with cabbage because water in which food is cooked is considered like that food. However, if a person vowed not to eat the water in which a certain food was cooked, he may still eat that food itself. One who vows not to eat sauce may eat the spices; one who vows not to eat the spices may eat the sauce. One who vows not to eat buckwheat is also prohibited the thick sauce that it generates.

Hilchos Nedarim 9:11

One who vows not to eat produce of the earth is prohibited all produce of the earth, but he may still eat fungi and mushrooms. If he vows prohibiting everything that grows on the earth, he is also prohibited fungi and mushrooms because, even though they aren’t nourished by the earth, they still grow on it.