What were the middle colonies called?

the corn colonies?

no

Check this site:

http://www.academickids.com/encyclopedia/index.php/Middle_Colonies

The middle colonies were a group of English colonies located in the middle region of what is now the United States. They were called the "middle colonies" due to their location between the New England colonies to the north and the Southern colonies to the south. The main middle colonies were Pennsylvania, New York, New Jersey, and Delaware. They were known for their diverse population, religious tolerance, fertile soil, and thriving trade.