Green,yellow and thread that matches the color of the bag,
felt in green and another color,
and ribbon/thin piece of felt.
cut a dome shape for the bag that is about 1 1/2 by 1/4. Cut a hole in one of the bag piece and a green piece that will cover it.
Sew the green piece over the hole and add some stitches of the green and yellow to make it look more like hay.
Now sew the bag pieces together,add a strap at the top and stuff.
Now give to your horse!