..Linen fibre for the vignette below.
Its cheap as one can get a whole wig for a couple of bucks. Its often found in plumber stores.
Cut some lumps in overlengt with a scissor. Take a small bunch between your thumb and forefinger. Again take the scissor and cut one end straight. The end you will dip in the glue.
Dip the end in white glue, dont overdo the dipping as there will be remains of glue left if one uses too much.
Press the end with the glue on the location and hold it as still as you can for 20-40 secons.
Then leave it for ca 5 minutes and when its starting to dry, you start dragin and pushing at the base to spread the straws out. That way it doesnt looks like the straws are having the same root.
When the glue has dried one can cut the grass to the desired length, trim it down and even comb it to straitghen it out and to remove straws thas hasnt been glued that well.
In the picture its in its natural colour but it can by dyed, airbrushed or drybrushed.
Hope this helps.