As far as fabric patterns goes, this is quite crisp.
Source Heliodor Jalba
This background has abstract texture with some similarities to wood.
Source V. Hartikainen
Looks a bit like concrete with subtle specks spread around the pattern.
Source Mladjan Antic
I have no idea what J Boo means by this name, but hey – it’s hot.
Source j Boo
A dark brown fabric-like background texture with seamless pattern of winding stripes.
Source V. Hartikainen
Prismatic Groovy Concentric Background 4 No Black
Source GDJ
The file was named striped lens, but hey – Translucent Fibres works too.
Source Angelica
A free seamless background texture of "timber wall" (colored in dark brown).
Source V. Hartikainen
Drawn in Paint.net and vectorised in Vector Magic
Source Firkin
Made by distorting a simple pattern using the 'sin waves' plugin for Paint.net and vectorising in Vector Magic
Source Firkin
You may use it as is, or modify it as you like.
Source V. Hartikainen
From a drawing in 'Jardyne's Wife', Charles Wills, 1891.
Source Firkin
A pattern derived from repeating unit cells each derived from part of a mosaic in paint.net. The starting point for the mosaic was a picture of some prawns!
Source Firkin
The tile this is based on can be had by selecting the rectangle in Inkscape and using shift+alt+i
Source Firkin
Remixed from a design seen on Pixabay. The basic tile can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
CC0 and a seamless pattern from a tile drawn in Paint.net .
Source SliverKnight
You just can’t get enough of the fabric patterns, so here is one more for your collection.
Source Krisp Designs
High detail stone wall with minor cracks and specks.
Source Projecteightyfive
Used a cherry by doctormo to make this seamless pattern
Source Firkin
From a drawing in 'At home', J. Sowerby, J. Crane and T. Frederick, 1881.
Source Firkin
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
This one is super crisp at 2X. Lined paper with some dust and scratches.
Source HQvectors
Embossed lines and squares with subtle highlights.
Source Alex Parker