So you want to make cool RPG Zines and have just discovered you can use paintings and illustrations under creative commons CC/public domain PD license. This are some advices around this kinda tricky thing. Here we go.
These guys are amazing. A lot of fine art stuff in huge resolutions and they make sure you know what is under creative commons and what is not.
This girl is a megazord curator from flickr and I love her work. She organizes everything in boards and everytime I wander around her work I came home with a bunch of ideas for new zines. Check her out.
Another great curator from flickr. More photographs than illustrations. A good source for your Cthulhu pulp zine.
Tons of cool stuff and old illustrations. Some classic fairy tale in here. Organized by boards as well.
This is a bloody awesome website. They have a public domain section and thousands and thousands of huge resolution images. You don't need an account to download and you have a daily limit for your downloads.
If Elusive Muse is the megazord, PDR is Zordon. They are marvelous. There are not enough words to describe their work.
This one is used a lot by graphic designers. It is totally photography focused, but you can make cool things out of it.
More than 180K images is enough for you? It is for me, hehe.
Never stop dreaming.
Make #ttrpg zines.