Not strictly seamless in that opposite edges are not identical. But they do marry up to make an interesting pattern
Source Firkin
The name alone is awesome, but so is this sweet dark pattern.
Source Federica Pelzel
A seamless background pattern of dark brown wood planks.
Source V. Hartikainen
The image a seamless pattern derived from a weed which I can't identify.The original weed image is from here:https://jp.pinterest.com/pin/500744052301423641/
Source Yamachem
To get the tile this is based on, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Prismatic Geometric Tessellation Pattern 4 No Background
Source GDJ
Seamless pattern the basic tile for which can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
Recreated from a pattern found in 'Az Osztrák-Magyar Monarchia irásban és képben', 1882. To get the tile this is based on select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
This is the remix of "Colorful Floral Pattern Background 3" uploaded by "GDJ". Thanks.
Source Yamachem
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
Here's a new paper-like background for free use on personal and commercial projects (this applies to all background patterns here).
Source V. Hartikainen
A pattern formed from a squared tile. The tile can be accessed in Inkscape by selecting the rectangle and using shift-alt-i.
Source Firkin
The file was named striped lens, but hey – Translucent Fibres works too.
Source Angelica
A re-make of the Gradient Squares pattern.
Source Dimitar Karaytchev
Remixed from an image on Pixabay uploaded by Prawny
Source Firkin
Prismatic Curved Diamond Pattern 7 No Background
Source GDJ
Looks like an old wall. I guess that’s it then?
Source Viahorizon
Prismatic Curved Diamond Pattern 2 No Background
Source GDJ
Alternative colour scheme. 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
Just like your old suit, all striped and smooth.
Source Alex Berkowitz
This is the remix of an OCAL clipart called "Art Nouveau ornament" uploaded by "microcosme".Thanks.This is a seamless pattern of an Art Nouveau ornament.
Source Yamachem
A bit like some carbon, or knitted netting if you will.
Source Anna Litvinuk
Prismatic Geometric Pattern Background
Source GDJ
Vector version of a png that was uploaded to Pixabay by pencilparker
Source Firkin
This reminds me of Game Cube. A nice light 3D cube pattern.
Source Sander Ottens
The image depicts a shell seamless pattern.I used an OCAL clipart called "Shell" uploaded by "jgm104".Thanks.
Source Yamachem