Apart from the 3 images that come with this default WordPress theme I have found https://pixabay.com/. Really nice images and they say:
You can copy, modify, distribute, and use the images, even for commercial purposes, all without asking for permission or giving credits to the artist.
https://pixabay.com/en/service/faq/
Wow. So I thought I’d at least mention them here if I am not going to be accrediting each image. 🙂
