Over the last couple of months I've made over 5,000 assets which you're absolutely free to use in your projects, both personal and commercial. I've made these assets to meet new people in the game development community and help out starting programmers without any artistic talent.
You can download most of these from my website, right here:
But it's easier to donate $1 USD (or more) below and receive them all in one giant package:
http://kenney.itch.io/kenney-donation
Let me know if you have any requests, I'll see what I can do
You can stay up-to-date on new assets on Twitter, Facebook or this thread.