Random images appearing in my home directory... Where are they coming from?

Solution 1:

No amount of investigation actually solved this but I did stop using Liferea and started using Lightread for reading my RSS feeds. The images stopped popping up.

Solution 2:

You can try running fatrace (see this answer) and when those images appear again, search for them in fatrace's log file. That hopefully will reveal the program that's acting up. :)