I read somewhere in a book that you can roll a piece of fondant or gp, whichever you're using until round and then toss it into some cornmeal which gives it a grainy look. Then you press down in the center. That'd be my suggestion.
you would need two sizes of daisy cutters (the larg and the small) and a center mold to make them look exactly like that. Alternatively you can use a piece of fine tulle to make an impressing on a small disk of gumpaste to mimic the center.
Thanks for your help!
I think I read somewhere on CC that tip #233, the grass tip, was used for the center imprint.