Snap! It’s a pattern, and it’s not grayscale! Of course you can always change the color in Photoshop.
Source Atle Mo
White little knobs, coming in at 10x10px. Sweet!
Source Amos
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
Colorful Floral Background 3 No Black
Source GDJ
Smooth Polaroid pattern with a light blue tint.
Source Daniel Beaton
This was formed by distorting an image of a background on Pixabay.
Source Firkin
Derived from an image that was uploaded to Pixabay by mdmelo.
Source Firkin
Prismatic Groovy Concentric Background
Source GDJ
Derived from a corner decoration itself found as a jpg on Pixabay.
Source Firkin
This is a remix of "blue wave-seigaiha".I hope this subtle color version of Seigaiha would be suitable for background .
Source Yamachem
Seamless pattern formed from a tile that can be had by selecting the rectangle in Inkscape and using shift-alt-i.
Source Firkin
Prismatic Polka Dots Mark II No Background
Source GDJ
Background Wall, Art Abstract, Block Well & CC0 texture.
Source Ractapopulous
Utilising some flowers from Almeidah. To get the unit tile, select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
A seamless pattern recreated from an image on Pixabay. It is reminiscent of parquet flooring and is formed from a square tile, which can be recovered in Inkscape by selecting the ungrouped rectangle and using shift-alt-I together.
Source Firkin
One more brick pattern. A bit more depth to this one.
Source Benjamin Ward
A seamless web background with texture of aged grid paper.
Source V. Hartikainen
Imagine you zoomed in 1000X on some fabric. But then it turned out to be a skeleton!
Source Angelica
From a drawing in 'Real Sailor-Songs', John Ashton, 1891.
Source Firkin
This was formed by distorting an image of a background on Pixabay.
Source Firkin
A seamless pattern from a tile drawn in Paint.net and vectorised in Vector Magic
Source Firkin
An alternative colour scheme to the original seamless pattern.
Source Firkin
A repeating background of thick textured paper. Actually, it turned out to look like something between a paper and fabric.
Source V. Hartikainen
Prismatic Abstract Geometric Background 4 No Black
Source GDJ