I suspect that this is a custom value list. If so, define a new table with at least two fields, Grade, Grain.
Create records in this table for each entry in your custom value list. Put the number in Grade and the text in Grain.
Define your value list to list Grade in field 1 and Grain in Field 2.
Use manage | Database | relationships to create this relationship (Use your table and field names here)
MainTable::Grade = NewTable::Grade
Format MainTable::Grade with this new value list. Put the NewTable::Grain field next to it on your MainTable based layout. When you select a grade in the MainTable::Grade field, the matching Grain text from the new table will automatically appear next to it.
Yeah this made me realize the value list method is fairly inefficient considering I could have a value list create itself based on the Grain table. Thank you Phil.