Other suggestions and comments:
Please read ""Heart cookies, Giant sized" both item And review for some details...

but the basic premise is: whether working with sugar cookies, cake layers, or construction paper: 3 heart-shapes, placed Points Together, equals a Shamrock Shape. (4 hearts=4 leaf clover ;-)

Green frosting, of course...and you can also use green sprinkles/candies/sugar.

Some of us luv Green M&M's but getting just the greenies can be a challenge! ;-) You might pick all the greenies out of a bag o' mini M&M's, though ;-)