If you have a local used book store see if they have any used national geographic books/magazines. They put out a lot of hard cover photo books for years and they are usually inexpensive and personally seeing an image in print is much better than on a screen.

500px used to be pretty good I am not sure how it is anymore.

Colossal has a nice featured photography section here that I really like and it has a wider variety than some other photography blogs.

If you want good photography by amateurs vs. professionals I also like looking at the winners of https://www.dpchallenge.com/ competitions.