You ask: where are they? So I answer.
1. Ask your friends and acquaintances.
People like photographing and they have interesting pictures which you may look for. Just talk to them. Once I needed a photo of giraffe and it appeared that my friend was at safari and had exactly what I wanted.
2. Contact to a photographer.
Look around and google and you’ll find photographers who share their pictures. Write to them and ask for permission to use a picture. For them it is also promotion, so you it is a good deal for both of you.
3. Take yourself.
Yes, take pictures yourself if you like. Think of a good course for beginners to know basic rules and do it yourself. Now you do not have to spend money on a good camera if you don’t wish as we have mobile phones that take pictures. Learn, experiment and built your own bank of pictures.
4. Use free photos.
Here 2 interesting searches:
I usually use my own pictures, but also use: Remember to choose CC license. Here more website where you can find interesting pictures:
Photo: Mira Huseva at a photo course by Jacek Kutyba.blog, photo, photography, picture, post