Marbleize 2 colors of fondant, or white and a colored fondant, as desired. Roll a 6 to 8-in. long x 3/8 in wide fondant rope. Twist and curl rope in desired shape; allow to dry on cornstarch-dusted cake circle, supporting heads, tails, etc. in a lifted position with pieces of crumpled aluminum foil. Roll 1/16 in. balls of white fondant eyes; attach to snakes with damp brush; let dry. Use FoodWriter marker to add black dot pupils.
Bake and cool a 2-layer 9-in. round cake. Stack cooled cake layers on a foil-wrapped cake board using buttercream icing as a filling; spatula ice stacked cake with green buttercream.
Tint buttercream icing 3-4 different shades of green. Place in decorating bags fitted with Tip 233; cover top of cake with varying shaded patches of pull-out grass. Add pull-out grass bottom border on cake. Arrange fondant snakes in the grass.