The green fibers pattern will work very well in grayscale as well.
Source Matteo Di Capua
Remixed from a PNG that was uploaded to Pixabay by gingertea
Source Firkin
Adapted from a drawing in 'Line and form', Walter Crane, 1914.
Source Firkin
Love me some light mesh on a Monday. Sharp.
Source Wilmotte Bastien
Prismatic Groovy Concentric Background 3 No Black
Source GDJ
Prismatic Isometric Cube Wireframe Pattern No Background
Source GDJ
Derived from an image that was uploaded to Pixabay by Kaz
Source Firkin
The image is a seamless pattern of a fishnet.
Source Yamachem
From a tile that can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
A new take on the black linen pattern. Softer this time.
Source Atle Mo
From a drawing in 'Resa i Afrika, genom Angola, Ovampo och Damaraland', P. Moller, 1899.
Source Firkin
Dark pattern with some nice diagonal stitched lines crossing over.
Source Ashton
This is so subtle: We’re talking 1% opacity. Get your squint on!
Source Atle Mo
A seamless background tile of aged paper with shabby look.
Source V. Hartikainen
A grid of squares with green colours. Since the colours are randomly distributed it is automatically seamless.
Source Firkin
Remixed from a design on Pixabay. To get the tile this is based on select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
Used correctly, this could be nice. Used in a bad way, all hell will break loose.
Source Atle Mo
The unit cell for this seamless pattern can be had in Inkscape by selecting the rectangle and using shift+alt+i.
Source Firkin
Here's a subtle marble-like background for use on websites.
Source V. Hartikainen
You know I’m a sucker for these. Well-crafted paper pattern.
Source Mihaela Hinayon
This is the remix of "blue wave-seigaiha".The image depicts a seamless pattern of the front upper part of Japanese five yen coin which is used currently.This design represents a rice with ripe golden ears.
Source Yamachem
Drawn in Paint.net using the kaleidoscope plug-in and vectorised.
Source Firkin
Prismatic Groovy Concentric Background 4 No Black
Source GDJ
As simple and subtle as it gets. But sometimes that’s just what you want.
Source Designova