Perhaps you should try some spelling variations:
"prairie corn grass" » "prairie town grass", "prairie dogs grass", "prairie vole grass", "prairie corn grains", "prairie corn grain", "prairie corns grasses"
"prairie cord grass" » "prairie dogs grass", "prairie vole grass", "prairie art grass", "prairie bird grass", "prairie cord graft", "prairie cord gray"
"prairie city grass" » "prairie city grades", "prairie city gas", "prairie city grand"

Try widening your search to All Fields.

You may be able to get more results by adjusting your search query.

• If you are trying to use Boolean operators, they must be ALL CAPS: (("prairie corn grass") OR ((("prairie cord grass") OR ("prairie city grass")))).
• The words AND, OR and NOT may confuse the search; try adding quotes: "((\"prairie corn grass\") or (((\"prairie cord grass\") OR (\"prairie city grass\"))))".
• Removing quotes may allow a broader search: (( prairie corn grass ) or ((( prairie cord grass ) OR ( prairie city grass )))).
• Adding a wildcard symbol may retrieve word variants: (("prairie corn grass") or ((("prairie cord grass") OR ("prairie city grass"))))*.