Remixed from a drawing in 'In an Enchanted Island', William Mallock, 1892.
Source Firkin
A pale olive green background with a seamless texture.
Source V. Hartikainen
This was formed by distorting an image of a background on Pixabay.
Source Firkin
The square tile this is based on can be had by selecting the rectangle in Inkscape and using shift+alt+i
Source Firkin
A dark metal plate with an embossed grid pattern and a bit of rust. Here's a dark metal plate texture for use as a tiled background on web pages.
Source V. Hartikainen
Prismatic Groovy Concentric Background No Black
Source GDJ
This one takes you back to math class. Classic mathematic board underlay.
Source Josh Green
A seamless green background texture. The image is distributed under a Creative Commons License (like all of the images here).
Source V. Hartikainen
Zero CC tileable hard cover cells book texture, 4k, scanned and made by me. CC0
Source Sojan Janso
An interesting dark spotted pattern at an angle.
Source Hendrik Lammers
A seamless pattern created from a square tile. To get the tile, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin
From a drawing in 'Sun Pictures of the Norfolk Broads', Ernest Suffling, 1892.
Source Firkin
Prismatic Groovy Concentric Background 4
Source GDJ
Medium gray pattern with small strokes to give a weave effect.
Source Catherine
This seamless web background texture looks like gray stone. It's great for using as a background image on web pages, or on some of their elements. Anyway, I hope you will find use for it.
Source V. Hartikainen
Derived from elements found in a floral ornament drawing on Pixabay.
Source Firkin
Prismatic Hypnotic Pattern No Background
Source GDJ
Prismatic Curved Diamond Pattern 4 No Background
Source GDJ
Derived from an image that was uploaded to Pixabay by darkmoon1968
Source Firkin
A dark striped seamless pattern suitable for use as a background on websites.
Source V. Hartikainen