From Ground: First, water the mouse-ear cress plant well to help maintain the integrity of the root ball. Then, using a spade or shovel, carefully dig a trench around the mouse-ear cress, taking care not to damage the root system. Once the trench is wide enough, gently lift the plant out of the ground.
From Pot: Water the mouse-ear cress thoroughly to ensure easy removal without damage to the roots. Turn the pot on its side and gently tap until the mouse-ear cress slides out with the soil and root ball intact. If the plant doesn't come out easily, give it more water and try again after the soil had some time to soak.
From Seedling Tray: If your mouse-ear cress is in a seedling tray, water it well. Then, while supporting the plant gently at stem, push upwards from the bottom of the tray to pop the plug of compost containing the seedling out.