The Holy Bible says that John ate something called "locusts":
"And John was clothed with camel's hair, and with a girdle of a skin about his loins; and he did eat locusts and wild honey" (Mark 1:6).
However, it is important to realize that the term "locust or locusts" is defined as "Any of numerous grasshoppers" AND IT IS ALSO DEFINED AS --> "Any of several similar or related trees, such as the honey locust or the carob."
The "Carob Tree" is native to the Mediterranean region. It has edible seed pods, which are known (especially in the related area) as "St. John’s Bread".