Tiny circle waves, almost like the ocean.
Source Sagive
A textured blue background pattern with vertical stripes.
Source V. Hartikainen
And some more testing, this time with Seamless Studio. It’s Robots FFS!
Source Seamless Studio
From a drawing in 'In an Enchanted Island', William Mallock, 1892.
Source Firkin
A version without colours blended together to give a different look.
Source Firkin
This background pattern looks like bamboo to me. Feel free to download it for your website (for your blog perhaps?).
Source V. Hartikainen
Remixed from a drawing that was uploaded to Pixabay by ractapopulous
Source Firkin
He influenced us all. “Don’t be sad because it’s over. Smile because it happened.”
Source Atle Mo
Zero CC asphalt, pavement, texture, photographed and made by me. CC0 WARNING I FOUND A SEAM ON THIS TEXTURE
Source Sojan Janso
This pack of filters can help you adding a blocky overlay to objects. May come handy at drawing blocks of stone.
Source Lazur URH
Inspired by a 1930s wallpaper pattern I saw on TV.
Source Firkin
Seamless pattern the tile for which can be had by using shift-alt-I on the selected rectangle in Inkscape.
Source Firkin
The image depicts an edo-era pattern called "same-komon" or "鮫小紋"which looks like a shark skin.The "same" in Japanese means shark in English.
Source Yamachem
From a drawing in 'Friend or Fortune? The story of a strange year', Robert Overton, 1897.
Source Firkin
A free seamless background texture that looks like a brown stone wall.
Source V. Hartikainen
A seamless pattern from a tile drawn in Paint.net and vectorised in Vector Magic
Source Firkin
You know you can’t get enough of these linen-fabric-y patterns.
Source James Basoo
Small gradient crosses inside 45-degree boxes, or bigger crosses if you will.
Source Wassim
From a tile that can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
Just what the name says, paper fibers. Always good to have.
Source Heliodor jalba
Just to prove my point, here is a slightly modified dark version.
Source Atle Mo
Pattern Background, Texture, Photoshop Structure style CC0 texture.
Source Darkmoon1968
A seamless pattern formed from a square tile based on a jpg on Pixabay. The tile can be retrieved by selecting the rectangle in Inkscape and using shift-alt-I.
Source Firkin