Step One:
Hoe a flat, 9x9 square of dirt.

Step Two:
In the middle of the square, knock out a dirt block and throw in a source of water.

Step Three:
Build a 3 high wall of any building block around your 9x9 square.

Step Four:
At any block inside of your wall, place a button that is eye-level.

Your wheat farm should look like this now:


Congrats if your wheat farm looks like this. Let's continue.

Step five:
On the outside of your wall, place a redstone torch on the same block as the button.

It should look like this


For redstone people: This creates an inversion which allows for redstone lamps to be on unless the button is pressed.

Step Six:
Place a block on top of the redstone torch.

Step Seven:
Build a roof high enough so you can just walk into the wheat farm.

Step Eight:
Place 5 redstone lamps and 1 redstone dust in this orientation:


Step Nine:
Place redstone dust so all of the Lamps are lit.


Step Ten: Make a 2 high 1 wide section of the wall dirt so you can easily enter and exit the farm.
NOTE: If you want the wheat to destroy, you NEED to have NO source of outside light. This means the room must be completely enclosed.

Step Eleven: Plant your seeds.


Step Twelve:
Wait for the wheat to grow.


Step Thirteen:
Press the Button and Enjoy!


Thanks for looking at my tutorial! If you found this helpful please comment/diamond :).

If you want to know how this works, continue.

Wheat destroys itself when it is exposed to very low light levels. The button causes the redstone lamps to temp. turn off, therefore, the wheat destroys itself completely, leaving the items on the ground.