Mill Stone

The Mill Stone is a very important block that you (might) use for the duration of your playthrough. It can be used to grind up plants and other substances into dye, wheat into flour, and to create grout or porcelain clay. In other words, very useful. You can craft it using seven (7) stone (not cobblestone), one (1) stone slab, and one (1) Grindstone (which you should already have/know how to make from previous Advancements).

Once you have crafted the mill stone, you will need to power it. This can be done using a Hand Crank at first in Age 0, and upgraded to Water Wheel (BWM) power later in Age 1. The hand crank simply needs to be placed adjacent (next to) the mill stone, then right-clicked. It will rapidly drain your hunger bar, so make sure to have plenty of food. As soon as you get axles and a waterwheel, you can power the mill stone by inserting an axle into either the top or bottom of the mill stone.

After (eventually) hooking up the mill stone to water power, you can easily automate its processes by placing hoppers down around it that connect to a chest, so that all that you have to do is put items into the mill stone, which will then be automatically collected and placed into the chest. Do be aware that the mill stone needs to have at least 3 sides uncovered in order for the items to come out, and the items have a tendency to fly wildly out if you're not careful with your setup.