If you're not into picture (landscapes, buildings, etc) wallpapers that other apps like Autowallpaper (for reddit) provides and like the more simpler and colorful wallpapers you might want to check out Blur. It's a simple idea, the premise of blurring pictures, but by simply doing so you are able to create neat looking backgrounds which reminds me of some of the early default Nexus wallpapers.
It's free in the Google Play store and I would recommend checking it out. There is also a paid version for $0.99 which allows you to adjust colors and is ad free.
