Affiliate Marketing Secrets

I’m running a paid membership site. I want to give my members access to content that is scattered across the internet, and organize it in one location for them.
Some of that content would be free. Some of the content would be offered to them at a steep discount (since they already paid to be a member of my site, they need perks).
Free Content
Are e-books, articles, videos, etc. that are readily available across the internet up for grabs? Can I use these without permission?
Discounted Content
I’m planning on just being an affiliate for these.
Any product, service, or information relating to making money would be appropriate here.
***Please point me in the direction of open, free content on the internet, that I can use without permission.***
Thanks!