Thanks for getting back so quickly. Here’s what I found:
jbf@gardenhousepi:~ $ lsb_release -a
No LSB modules are available.
Distributor ID: Raspbian
Description: Raspbian GNU/Linux 9.4 (stretch)
jbf@gardenhousepi:~ $ groups jbf
jbf : jbf
jbf@gardenhousepi:~ $ cat /etc/group | grep spi
I added my username (jbf) to the /etc/group, and tried it again, but I still get a permission error. Is it a different group that I should use? …Okay, I did log in as user pi and I can see now that it works. I should be able to figure out what the difference is. Thanks!