As you said in your answer to your own question,
salt '*' pillar.data
will show all the data. However, you have some additional useful commands:
salt '*' pillar.raw
will show the raw data as it's loaded into the __pillar__
dict.
salt '*' pillar.get <key>
will show you the value of some key in pillar, with the ability to default to a certain value if the key doesn't exist. (The default is super useful when you're using pillar when templating states)