For grassy footsteps I have used newspaper in a plastic grocery bag and softly tapped the bag. It worked out pretty well.
– Spencer Johnson
Old cassette tape – unravel a few tapes and put the tape on different surfaces (carpet, stone etc) and walk on it. Also just rotating it between your hands.
– Mark Estdale
I think a wet sponge or rag with the right timing (heel / toes) will do the job.
– Manuel Laval
The best way I found to get the sound I wanted was to fill a 4×2 plastic case with earth and water. We actually made the footsteps with our hands in it.
– Jerome Boiteau
There are different kinds of grass – green grass and dry grass. People have already mentioned cassette tape for grass but I feel that this sounds exclusively like dry grass. For green grass I use military camouflage. Sounds great and doesn’t compress losing its depth and texture.
– Chris Piggins