An attempt for cleaning up the original image in a few steps.
Source Lazur URH
A grid of squares with green colours. Since the colours are randomly distributed it is automatically seamless.
Source Firkin
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
A seamless texture of worn out "cardboard".
Source V. Hartikainen
From a drawing in 'At home', J. Sowerby, J. Crane and T. Frederick, 1881.
Source Firkin
Geometric lines are always hot, and this pattern is no exception.
Source Listvetra
Prismatic Groovy Concentric Background No Black
Source GDJ
The tile this is formed from can be retrieved in Inkscape by selecting the rectangle and using shift+alt+i
Source Firkin
Prismatic Groovy Concentric Background 5
Source GDJ
Seamless Prismatic Geometric Pattern With Background
Source GDJ
Not a pattern for fabrics, but one produced from a jpg of a stack of fabric items that was posted on Pixabay. The tile that this is based on can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
On a large canvas you can see it tiling, but used on smaller areas, it’s beautiful.
Source Paul Phönixweiß
Lovely pattern with splattered vintage speckles.
Source David Pomfret
The original enhanced with one of Inkscapes's filters.
Source Firkin
Floral patterns will never go out of style, so enjoy this one.
Source Lasma
Not strictly seamless in that opposite edges are not identical. But they do marry up to make an interesting pattern
Source Firkin
Simple gray checkered lines, in light tones.
Source Radosław Rzepecki
A repeating background of thick textured paper. Actually, it turned out to look like something between a paper and fabric.
Source V. Hartikainen
Dark, square, clean and tidy. What more can you ask for?
Source Jaromír Kavan
This ladies and gentlemen, is texturetastic! Love it.
Source Adam Pickering