From memory of an old RR magazine article- asparagus fern. This was found in a craft store and i believe its made of plastic and used as a filler plant for arrangements. The stalk was cut to height and the the round leaves were squished flat with pliers.
The author also noted that it would be rather time consuming to make a field, he used it for a garden plot which was smaller in size.
I would consider this info a steer in direction. Maybe best to double check it before ordering a bunch site unseen online or something