The image depicts a shell seamless pattern.I used an OCAL clipart called "Shell" uploaded by "jgm104".Thanks.
Source Yamachem
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin
Super simple but very nice indeed. Gray with vertical stripes.
Source Merrin Macleod
A seamlessly tile-able grunge background image.
Source V. Hartikainen
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 'The Quiver of Love', Walter Crane, 1876
Source Firkin
This one takes you back to math class. Classic mathematic board underlay.
Source Josh Green
A repeating background with a look of paper. I have added some changes to PatCreator. Now you can share your designs by submitting them to a new gallery section. Start by clicking Edit with PatCreator above.
Source V. Hartikainen
Zero CC bark from fur tree tileable texture, photographed and made by me. CC0
Source Sojan Janso
Drawn in Paint.net using the kaleidoscope plug-in and vectorised.
Source Firkin
A free background pattern with abstract green tiles.
Source V. Hartikainen
Prismatic Groovy Concentric Background 4
Source GDJ
A seamless pattern formed from miutopia's cakes on a tablecloth.
Source Firkin
From a drawing in 'Resa i Afrika, genom Angola, Ovampo och Damaraland', P. Moller, 1899.
Source Firkin
Prismatic Polka Dots 3 No Background
Source GDJ
Design drawn in Paint.net, vectorised using Vector Magic and finished in Inkscape.
Source Firkin
Utilising some flowers from Almeidah. To get the unit tile, select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
As simple and subtle as it gets. But sometimes that’s just what you want.
Source Designova
Not even 1kb, but very stylish. Gray thin lines.
Source Struck Axiom
Remixed from a drawing in 'The March of Loyalty', Letitia MacClintock, 1884.
Source Firkin
Prismatic Curved Diamond Pattern 3 No Background
Source GDJ
This was formed by distorting an image of a background on Pixabay.
Source Firkin
Based on several public domain drawings on Wikimedia Commons. This was formed from a rectangular tile. The tile can be accessed in Inkscape by selecting the rectangle and using shift-alt-i.
Source Firkin