Sources for  Free Images

Pixabay – has a huge selection including photos and even vectors.  Attribution is not required (even for commercial use)  and you are allowed to alter the image. While attribution is not required it is always appreciated.
Pixabay License Info

Unsplash – Huge selection of high-quality photos.  Free use for both commercial and non-commercial purposes. Attribution is not required but is appreciated. They even give you a copy and paste option for attribution when you download.
Unsplash License Agreement

Pexels:  Another great site. Images are free to download and you are allowed to alter them. Attribution is not required but is appreciated.
Pexels License Agreement

Colour Resources

Adobe Color:  This free adobe resource duplicates and extends many of the color functions you find in the adobe programs: the color guide, the edit color wheel, etc.  I love playing with colors on this site as I get a full-screen view rather than the smaller display from within Illustrator. Upload a photo to extract a color palettes or gradients. Tweak the colors with the color wheel using the color harmonies and further customize with the color sliders.

You can also explore color pallets created by others, trending colors, and check your palette for contrast and usability for those with various forms of color blindness. This web app integrates with your Adobe Stock account colors and gradients in your stock libraries.

Image Colour Picker: Upload photos and make color palettes from your photos but… I find the real power comes in the color picker tab – use it to show both tints and shades and a variety of color combinations based on your original color.