CC0 and a seamless pattern from a tile drawn in Paint.net .
Source SliverKnight
Light square grid pattern, great for a “DIY projects” sort of website, maybe?
Source Rafael Almeida
A frame using leaves from an image that was uploaded to Pixabay by mayapujiati
Source Firkin
This background pattern contains worn out colorful stripes as a texture.
Source V. Hartikainen
Snap! It’s a pattern, and it’s not grayscale! Of course you can always change the color in Photoshop.
Source Atle Mo
A seamless textured paper for backgrounds. Colored in pale orange hues.
Source V. Hartikainen
Prismatic Abstract Geometric Background 5 No Black
Source GDJ
Prismatic Abstract Background Design No Black
Source GDJ
Can never have too many knitting patterns, especially as nice as this.
Source Victoria Spahn
Remixed from a drawing in 'The March of Loyalty', Letitia MacClintock, 1884.
Source Firkin
Derived from elements found in a floral ornament drawing on Pixabay.
Source Firkin
Sharp diamond pattern. A small 24x18px tile.
Source Tom Neal
Remixed from a drawing in 'Hungary. A guide book. By several authors', 1890.
Source Firkin
From a drawing in 'Sun Pictures of the Norfolk Broads', Ernest Suffling, 1892.
Source Firkin
Prismatic Floral Pattern 3 Variation 3 No Background
Source GDJ
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
Seamless , tileable CC-0 texture. Created by my own, feel free to use wherever you want!
Source Linolafett
Colorful Floral Background 3 No Black
Source GDJ
A subtle shadowed checkered pattern. Increase the lightness for even more subtle sexiness.
Source Josh Green
Seamless pattern formed from a tile that can be extracted by selecting the rectangle in Inkscape and using shift-alt-i.
Source Firkin
A tile-able background for websites with paper-like texture and a grid pattern layered on top of it.
Source V. Hartikainen
You can never get enough of these tiny pixel patterns with sharp lines.
Source Designova