Mobile SMS app background images

I am developing a mobile SMS app and want to allow the user to use custom background images. I am looking for a total of 5 different background images to start with (potential for much more work). I attached a file of some concepts I like. I am looking for more or less subtle images that don't overpower the SMS message thread. The overall size of each image should be 3840 width by 2160 height. This will allow me to scale down to smaller phone resolutions. Please include any portfolio work you have completed so I can gauge your skill level and get an idea of the kind of graphic work you do.