Hello Reand,
Certainly, the best way to go about "creating" textured backgrounds is to begin by photographing appropriate materials: rock, metal, paper, plant material, water, sky etc.
Some time back I photographed, or gathered from other sources, a collection of textural images and share them on Google Drive. The direct purpose, at the time, was to use as layered overlays in the Layers module of PhD. Many of them would suit your purposes, &
they're still available.
I've, just now, uploaded a
different set of images photographed/collected for the same purpose. With some blurring, & other effects, they'd be suitable as backdrops rather than overlays.
Along with other forum members, I applaud
Eric's work & generosity in sharing his creations in photography, music & video.
PIX
PIX YouTube channel