People seem to enjoy dark patterns, so here is one with some circles.
Source Atle Mo
A subtle shadowed checkered pattern. Increase the lightness for even more subtle sexiness.
Source Josh Green
Not sure if this is related to the Nami you get in Google image search, but hey, it’s nice!
Source Dertig Media
From an image on opengameart.org shared by rubberduck.
Source Firkin
Pass parameters to the URL or edit the source code variables to configure the graph paper for the division desired.
Source JayNick
Utilising some flowers from Almeidah. To get the unit tile, select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
Formed by distorting a JPG from PublicDomainPictures
Source Firkin
This background pattern contains a seamless texture of bark. It's not very realistic, but I think it looks quite nice.
Source V. Hartikainen
The image depicts the Japanese Edo pattern called "seigaiha" or "青海波" meaning "blue -sea- wave".I hope it's suitable for the summer season.
Source Yamachem
This background image has seamless texture that resembles a surface of gray stone.
Source V. Hartikainen
Inspired by a pattern seen on a public domain image of a very old tile. To get the unit cell, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Prismatic Triangular Seamless Pattern III With Background
Source GDJ
This is a seamless pattern which is derived from a flower petal image.
Source Yamachem
Prismatic Geometric Tessellation Pattern 2 No Background
Source GDJ
Alternative colour scheme for the original floral pattern.
Source Firkin
Design drawn in Paint.net, vectorised using Vector Magic and finished in Inkscape.
Source Firkin
A background tile of dark textile. Made this a long time ago and just now decided to publish it.
Source V. Hartikainen
Remixed from a drawing in 'Chambéry à la fin du XIVe siècle', Timoleon Chapperon, 1863.
Source Firkin
Here's an yet another seamless note paper texture for use as a background on websites.
Source V. Hartikainen
From a drawing in 'Artists and Arabs', Henry Blackburn, 1868.
Source Firkin
Abstract Tiled Background Extended 12
Source GDJ