I tried to pull out the list of resource sites @theluthier featured in the Sourcing Third Party Material in Your Work livestream, as well as add some others I know. I don't know if this is posted somewhere else — I couldn't find it when I looked, but I thought it might be helpful.
Since the forum doesn't like a post full of links, however, I've pulled it out into a Google Doc you can find at https://hdp.rocks/freeresources
Also, if you get a Blender Cloud subscription (about $10/mo right now), you can have access to their library of textures, HDRi, and characters.
I'll try to remember to update the doc as I find new stuff.
Excellent initiative, hdpeterson! Thanks for putting the links into a convenient list. I wonder if I could embed that google doc into the description of that archived live stream 🤔
@theluthier As far as I'm concerned you can. Maybe pin the post, too. It's free to share wherever it's most useful. :)