There is real value in burying pennies in your lawn, as they contain copper, a valuable nutrient that also works as a simple and effective antimicrobial and antifungal tool.
Copper is a necessary element for photosynthesis, as it supports respiration, stimulates the function of enzymes, and even helps with building cell walls.
If you have some old pennies lying around (especially those from before 1837), place a few into the dirt around your yard to improve soil quality and make the slugs leave.
Aim to push the pennies into the soil at least 2 centimeters deep. Doing this on a day after it rains when the soil is soft may make it a bit easier to do.
If your lawn has significant fungal or moss development, take a small ball, rock, or other item and glue pennies along the outside of it. Use this to spot-treat your lawn.
You may need more copper in the soil if you notice limited growth and development of blades; damage to the young, sprouting grass; and twisting of the blades.