This seamless background image should look nice on websites. It has a dark blue gray texture with vertical stripes, it tiles seamlessly and, like all of the background images here, it's free. So, if you like it, take it!
Source V. Hartikainen
Remixed from a drawing in 'Analecta Eboracensia', Thomas Widdrington, 1897.
Source Firkin
This is a semi-dark pattern, sort of linen-y.
Source Sagive SEO
Zero CC tileable cork floor, photographed and made by me. CC0
Source Sojan Janso
Imagine you zoomed in 1000X on some fabric. But then it turned out to be a skeleton!
Source Angelica
From a drawing in 'Line and form', Walter Crane, 1914.
Source Firkin
This one is something special. I’d call it a flat pattern, too. Very well done, sir!
Source GetDiscount
This is the remix of "Colorful Floral Pattern Background 3" uploaded by "GDJ". Thanks.
Source Yamachem
To get the tile this is based on select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
To get the tile this is formed from select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
A seamless pattern with a unit cell drawn as a bitmap in Paint.net and vectorized in Vector Magic.
Source Firkin
To get the tile this is based on, select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
Nasty or not, it’s a nice pattern that tiles. Like they all do.
Source Badhon Ebrahim
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin
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
Prismatic Geometric Tessellation Pattern 3 No Background
Source GDJ
Colorful Floral Background 3 No Black
Source GDJ
Made by distorting a simple pattern using the 'sin waves' plugin for Paint.net and vectorising in Vector Magic
Source Firkin
From a drawing in 'Two Women in the Klondike', Mary Hitchcock, 1899.
Source Firkin
Super subtle indeed, a medium gray pattern with tiny dots in a grid.
Source Designova
Continuing the geometric trend, here is one more.
Source Mike Warner
Drawn in Paint.net and vectorised in Vector Magic.
Source Firkin
Looks a bit like concrete with subtle specks spread around the pattern.
Source Mladjan Antic
Horizontal and vertical lines on a light gray background.
Source Adam Anlauf
Prismatic Snowflakes Pattern 2 No Background
Source GDJ