I've been doing this for years but also and primarily using manila and other various forms of natural (or at least non shiney plastic/nylon) rope materials. It is kind of a staple for doing a railway modelled in a prairie landscape. It is easy, effective and very cheap by MR standards - meaning monetarily. You can buy a lifetime supply of manila for a few measily dollars compared to MR grass.
Simply cut and glue for dead or fall grass, or dye, cut and glue for coloured or fresh grasses. One of the best most effective tall grass modelling techniques out there.
I have always had a low (pretty much non existant) budget for trains so had to learn to be resourceful from an early age. There are many natural and free sources for scenicking materials out there if a person is willing to look, research or just plain try different things. Your hard earned money can then be directed to more important things like rolling stock or locomotives.
Another great natural ingredient is what I call Old Man's Beard (a kind of tall yellow flower that goes to a white fuzz in fall) - the small inner leaves of it make great HO guage cat tails and bull rushes...
If I had the time I would would make a list of useful dried plants for MR scenery, but I would have to research all the proper names for them and post pics for ID if it was going to be any use to anyone. A big task. If I remember some of them I'll try to post them here for referance.
Good topic!