I write a lot about corn and how to use it, from corn meal to masa. Here are the tools you can use to grind the corn and other grains.
Modern Day Dry Grain Grinder
Two ridged cast iron or stone plates grind together when a hand crank is turned or electric mechanism is engaged. These grinders grind all types of dry grains such as wheat, corn, etc or even nuts into a course cracked texture to a fine milled flour.
Modern Day Masa Grinder
These grinders are similar to dry grain grinders but the plates are slightly different and are used for grinding masa. Masa is the product you get after grinding wet nixtamalized corn (hominy). Check out my post on how to make hominy step by step! Here is a link for the masa grinder.
Manos y Metate (grinding stone)
Manos y Metate were used in Central America and South America, similar grinding stones were used all over the world for centuries. Made up of a flat stone and a cylinder shaped stone rolled over to grind wet masa and dry grains. They can also be imbedded in large rocks.
Mortar and Pestle (corn pounder)
A stone or wooden bowl and a stick like pounder. Small ones can be used for grinding herbs and spices while large ones can pound dry grains. Some corn pounders are made from hollowed out and burnt tree stumps.