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
You know I love paper patterns. Here is one from Stephen. Say thank you!
Source Stephen Gilbert
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
Submitted in a cream color, but you know how I like it.
Source Devin Holmes
A set of paper filters. The base texture is generated the same way, only the compositing mode is varied.
Source Lazur URH
A background pattern inspired by designs seen in 'Burghley. The Life of William Cecil', William Charlton, 1857.
Source Firkin
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
Remixed from a drawing in 'Sun Pictures of the Norfolk Broads', Ernest Suffling, 1892.
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
A seamless pattern from a tile drawn in Paint.net and vectorised in Vector Magic
Source Firkin
Prismatic Geometric Pattern Background 2
Source GDJ
Use shift+alt+i on the selected rectangle in Inkscape to get the tile this is based on
Source Firkin
The first pattern on here using opacity. Try it on a site with a colored background, or even using mixed colors.
Source Nathan Spady
Cubes as far as your eyes can see. You know, because they tile.
Source Jan Meeus
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin
White little knobs, coming in at 10x10px. Sweet!
Source Amos
This one is rather fun and playful. The 2X could be used at 1X too!
Source Welsley
A topographic map like this has actually been requested a few times, so here you go!
Source Sam Feyaerts
The unit cell for this seamless pattern can be had in Inkscape by selecting the rectangle and using shift+alt+i.
Source Firkin
I guess this is inspired by the city of Ravenna in Italy and its stone walls.
Source Sentel