Is there a quick way to determine what all of the possible values for a field would be when I'm using it in a Report filter? For example, I want to use a field that is not an ordinary picklist as a filter in a report, but when I choose that field as a filter it does not automatically include all the possible choices for that field. A field such as Salutation or Rating it does show you all of the possible values to choose from, as those are picklists. A different filter such as "Delegated Approver" or "Login Status" don't provide any list of choices so you have to enter the exact words you're filtering for.
Only filters on Picklist fields will show you available filter values. Not on text or lookup fields.
However for one to view the available values in a particular non-picklist field, what I would do is create a report and add the relevant column to it.
Then add a Group report by column grouping, that would show you possible unique values in your concerned field. *unless there are blank/null values in it*