A seamless background pattern with a texture of wood planks. This wood background pattern has vertically arranged planks. You may try to rotate it 90°, to see how it will look like when the wood planks are arranged horizontally.
Source V. Hartikainen
A seamless pattern from a tile drawn in Paint.net and vectorised in Vector Magic
Source Firkin
Free tiled background with colorful stripes and white splatter.
Source V. Hartikainen
Seamless Prismatic Pythagorean Line Art Pattern No Background. A seamless pattern that includes the original tile (go to Objects / Pattern / Pattern To Objects in Inkscape's menu to extract it).
Source GDJ
From a tile that can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
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
Seamless pattern formed from a tile that can be had by selecting the rectangle in Inkscape and using shift-alt-i.
Source Firkin
Continuing the geometric trend, here is one more.
Source Mike Warner
This reminds me of Game Cube. A nice light 3D cube pattern.
Source Sander Ottens
A free seamless background image with a texture of dark red "canvas". It should look very nice on web sites.
Source V. Hartikainen
Formed by distorting the inside front cover of 'Diversæ insectarum volatilium : icones ad vivum accuratissmè depictæ per celeberrimum pictorem', Jacob Hoefnagel, 1630.
Source Firkin
Floral patterns might not be the hottest thing right now, but you never know when you need it!
Source Lauren
Bit of a strange name on this one, but still nice. Tiny gray square things.
Source Carlos Valdez
CC0 and a seamless pattern from a tile drawn in Paint.net .
Source SliverKnight
Everyone needs some stardust. Sprinkle it on your next project.
Source Atle Mo
Derived from elements found in a floral ornament drawing on Pixabay.
Source Firkin
Just to prove my point, here is a slightly modified dark version.
Source Atle Mo
I guess this is inspired by the city of Ravenna in Italy and its stone walls.
Source Sentel
Use shift+alt+i on the selected rectangle in Inkscape to get the tile this is based on
Source Firkin