The 2nd image from portfolio of Elizabeth Meyers. The purple flowers wallpaper can be downloaded under CC0 license. Check it at the optimal resolution for your project and with the right click save it for apply in phones, desktop backgrounds, blog articles, apps, web templates...
Widescreen Desktop / Macbook (Retina): 2880x1800 (fits on: 2560x1600, 1920x1200, 1440x900)
High Definition HD 1080p: 1920x1080 (fits on: 1600x900, 1366x768, 1280x720)
Samsung Galaxy Tab & iPad: 2048x2048 (compatible with many tablets)
HTC, Samsung Galaxy & iPhone: 1080x1920 (compatible with many phones)