What are the lymphatic tissues present under the mucous membrane which lines the nose, mouth and pharynx called?

Tonsils are lymphatic tissues that exist beneath the mucous membrane that lines the nose, mouth, and pharynx. They are found in the back of the mouth and at the pharynx's entrance. 

They are part of the body's immune system and aid in the filtering and trapping of potentially harmful substances such as bacteria and viruses before they enter the body. 

A mucous membrane covers the tonsils, which is similar to the mucous membranes that line other parts of the respiratory and digestive systems.