When using photos make sure to use photos under the Creative Commons license. Using any photo you want from the internet, even with credit, is not always allowed, and can be illegal.
Unless you know the photo is open to the public (Public Domain) and can be used under Creative Commons consider some other places to find photos.
Make sure you click on pictures and view owners of said pictures. Make sure you know what kind of license a picture has and if the person wants credit or not. Many pictures under Creative Commons do not require credit, but some do.
Using pictures from Pinterest you may not have permission to do so. Always know where the pictures original creator come from, and if you have permission.
Here are some sites I’ve found.
Flickr (Creative Commons Public Domain Area)
New Old Stock– Older photos from history free from copyright
🙂 Hope this helps!!!