This seamless pattern consists of a blue grid on a yellow background.
Source V. Hartikainen
Adapted from an image that was uploaded to Pixabay by Anerma.
Source Firkin
Derived from an image that was uploaded to Pixabay by darkmoon1968
Source Firkin
This one is super crisp at 2X. Lined paper with some dust and scratches.
Source HQvectors
To get the tile this is based on, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
It’s a hole, in a pattern. On your website. Dig it!
Source Josh Green
You may use it as is, or modify it as you like.
Source V. Hartikainen
Light and tiny, just the way you like it.
Source Rohit Arun Rao
You know I’m a sucker for these. Well-crafted paper pattern.
Source Mihaela Hinayon
A floral background formed from numerous clones of flower 117.
Source Firkin
From a drawing in 'Sun Pictures of the Norfolk Broads', Ernest Suffling, 1892.
Source Firkin
Cubes as far as your eyes can see. You know, because they tile.
Source Jan Meeus
Black And White Floral Pattern Background from PDP.
Source GDJ
A seamless design of flowers remixed from a jpg on Pixabay by Prawny.
Source Firkin
Inspired by a pattern found in 'A General History of Hampshire, or the County of Southampton, including the Isle of Wight', Bernard Woodwood, 1861
Source Firkin
CC0 and a seamless pattern from a tile drawn in Paint.net .
Source SliverKnight
Carbon fiber is never out of fashion, so here is one more style for you.
Source Alfred Lee
A bit of scratched up grayness. Always good.
Source Dmitry
Lovely pattern with some good-looking non-random noise lines.
Source Zucx
Floral patterns might not be the hottest thing right now, but you never know when you need it!
Source Lauren
From a drawing in 'Sun Pictures of the Norfolk Broads', Ernest Suffling, 1892.
Source Firkin
To get the tile this is made up from select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Like the name suggests, this background image consists of a pattern of dark bricks. It may be an option for you, if you are looking for something that looks like a brick wall for use as a background on web pages. It's not a masterpiece, but looks pretty nice when is tiled.
Source V. Hartikainen
A grid of squares with green colours. Since the colours are randomly distributed it is automatically seamless.
Source Firkin