From a drawing in 'Friend or Fortune? The story of a strange year', Robert Overton, 1897.
Source Firkin
Retro Circles Background 7 No Black
Source GDJ
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
A grid of squares with green colours. Since the colours are randomly distributed it is automatically seamless.
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
Looks like a technical drawing board: small squares forming a nice grid.
Source We Are Pixel8
Super dark, crisp and detailed. And a Kill Bill reference.
Source Badhon Ebrahim
Nice little grid. Would work great as a base on top of some other patterns.
Source Arno Gregorian
From a drawing in 'In an Enchanted Island', William Mallock, 1892.
Source Firkin
This was formed by distorting an image of a background on Pixabay.
Source Firkin
Orange-red pattern for tiled backgrounds.
Source V. Hartikainen
Inspired by a JPG that was uploaded to Pixabay by kokon_art
Source Firkin
Made by distorting a simple pattern using the 'sin waves' plugin for Paint.net and vectorising in Vector Magic
Source Firkin
To get the tile this is formed from select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
A seamless dark leather-like background texture with diagonal lines that look like stitches.
Source V. Hartikainen
The image depicts meshed silhouettes of various things.The original image is an OCAL clipart called "Enter FOSSASIA 2016 #IoT T-shirt Design Contest" uploaded by "openclipart".Thanks.
Source Yamachem
High detail stone wall with minor cracks and specks.
Source Projecteightyfive
From an image on opengameart.org shared by rubberduck.
Source Firkin
Seamless Background For Websites. It has a texture similar to cork-board.
Source V. Hartikainen