I searched for ages on Pinterest for websites that have copyright free images and one of the suggestions was http://www.pixabay.com
I love Pixabay! There are loads of free images, paid for suggestions if you want them, on just about every subject you can imagine. I put them into Canva (iOS app on the iPad) and create my Twitter and blog post images.
These are some examples that I have used recently. All the wording has been added by me in Canva.
If you upload 10 images you also get an advert free site. It’s free to join up, you can download the size of image you wish; small, medium, large, full size. All vary in file size obviously. You can donate via PayPal if you want to support the photographers.
So, if you are looking for a great range of images from some very talented photographers try Pixabay: http://www.pixabay.com