A penny bun is a type of mushroom that is also known by different names depending on the region. In the United States, it is called porcini, and in Italy, it is known as porcino. In France, it is referred to as cepe, and in Spain, it goes by boletus. Other synonyms for penny bun include king bolete, steinpilz, and porcino nero. Penny bun mushrooms are often used in culinary dishes and are highly coveted due to their intense, earthy flavor. Regardless of the name used, these delicious mushrooms are a popular choice among chefs and mushroom lovers alike.