From MothCraft

To create an autofarm, you can take an END_ROD and place it in the middle of some grass. An END_ROD can be crafted with a DROPPER and a DIAMOND_HOE in a workbench. the grass will convert to farmland and nyou can instantly plant things there. it will autoharvest and replant.. you can also use these farms to reproduce animals and collect eggs from chickens and stuff.

End Rods[autofarms] will be crafted with a diamond hoe and a dropper in any configuration.