Wool, Sheep farm, All versions

1. Dig a stairway until 3 blocks deep and then lengthen the staircase bottom by 1 block.

2. On the very bottom, add a chest infront and a hopper behind connected to the chest.

3. On top of the hopper, add a rail and then attach your minecart with hopper on the rail.

4. Place a grass block above the minecart and a dispenser, with your shears inside, 1 block above and behind the grass block. This will shear the sheeps wool.

5. Surround the same grass block with your glass blocks and lure/spawn your sheep inside the glass cage.

6. 1 block under and behind your dispenser, add an observer with the top arrow of the observer pointing towards your dispenser and then place redstone dust on top of the observer.

7.  When the sheep eats the grass block under itself it will grow wool and since the grass block changed it gets detected by the observer that sends a signal to the dispenser which shears the sheep and then the minecart with hopper below the sheep picks up the wool blocks and stores it inside the chest.