For me, Website Design and Graphic Design go hand in hand. I'm always searching for design elements to use on websites, logos, print materials etc. These design elements can come in many forms, but the most basic is the ICON. My favorite place to get icons is a website called Noun Project. I have had a premium subscription with them for years (The cost is currently $39.99/year).
Noun Project provides access to OVER 1 MILLION icons. The best part is their icons come in PNG (transparent background) and SVG (A vector format). This allows users to bring the file into Photoshop or Illustrator and easily manipulate it. I've used their icons on websites, logos, flyers, brochures and the list goes on. A simple search for the word "rain" in Noun Project produces over 9,000 search results.
If you're looking for stock icons for a project be sure to consider Noun Project.