How do I find my external pillar?

first-try.cfg

old/test-users.sls
new/customers.sls

#...where 'old' and 'new' are directories parralel to 'first-try.cfg', and
#    the files are in pillar format... that's beside the point at this stage
#    i think, since i don't even get errors that complain about them]

pillar.top.sls

saltlab04:
  - stack/first-try
  
#  [this is a guess, and wrong... either that, or something deeper
#   in my setup is failing to yield up any pillar-like data for us
#   to refer to here...]
 
# Refreshing my pillar suggests there's nothing to be seen here:
 
# $ sudo salt 'saltlab04*' saltutil.refresh_pillar
# saltlab04.chi5.prlss.int:
#    None

The minion sees nothing

$ time sudo salt-call pillar.items
local:
    ----------
    _errors:
        - Specified SLS 'stack/first-try' in environment 'base' is not available on the salt master

@mjinks, your pillar top file looks wrong. I would expect it to look like this:

base:
  saltlab04:
    - stack/first-try

To clarify: my top file does look like that; my initial post just left out 'base:' because there's lots else further up. (All of which has been working fine for months, and still does.) There's also some other pillar data in the minion's listing that does work fine currently, so this isn't a broad failure in my pillar.