I like this style of cake & know I've seen it in buttercream before, but i didn't have it saved. So, how would you go about piping the grass in buttercream? I'm thinking of just drop flowers, or if I have time to make little fondant flowers.
You could do the grass with a leaf tip - even open the tip up a bit so you don't get as much of a 'vein' down the middle.
Just a basic 'leaf tip' oughta do. Just stripe the sides with a long extending motion. I've made long blades of grass this way in the past when doing floral cakes at an 'all buttercream' type bakery.
a tip 67or 68 will give you similar look...kinda sorta...