list Postgres ENUM type

select enum_range(null::my_enum)

where my_enum is the enum type name.

Documentation: http://www.postgresql.org/docs/9.5/static/functions-enum.html

You can list the data type via

\dT+ channels

https://www.postgresql.org/docs/current/static/app-psql.html#APP-PSQL-META-COMMANDS

select n.nspname as enum_schema,  
       t.typname as enum_name,  
       e.enumlabel as enum_value
from pg_type t 
   join pg_enum e on t.oid = e.enumtypid  
   join pg_catalog.pg_namespace n ON n.oid = t.typnamespace;