Seamless pattern formed from a tile that can be extracted by selecting the rectangle in Inkscape and using shift-alt-i.
Source Firkin
Abstract Ellipses Background Grayscale
Source GDJ
The following orange background pattern resembles a honeycomb.
Source V. Hartikainen
Floral patterns will never go out of style, so enjoy this one.
Source Lasma
A seamless green background texture. The image is distributed under a Creative Commons License (like all of the images here).
Source V. Hartikainen
Derived from elements found in a floral ornament drawing on Pixabay.
Source Firkin
A seamless background colored in pale orange. It has a paper like texture with diagonal grid pattern.
Source V. Hartikainen
Retro Circles Background 8 No Black
Source GDJ
Submitted as a black pattern, I made it light and a few steps more subtle.
Source Andy
ZeroCC tileable stone texture, edited from pixabay, CC0
Source Sojan Janso
Remixed from a JPG that was uploaded to Pixabay by susanlu4esm
Source Firkin
Zero CC tileable cork floor, photographed and made by me. CC0
Source Sojan Janso
This is a seamless pattern of regular hexagon which has a honeycomb structure.
Source Yamachem
A background pattern inspired by designs seen in 'Burghley. The Life of William Cecil', William Charlton, 1857.
Source Firkin
From a drawing in 'Sun Pictures of the Norfolk Broads', Ernest Suffling, 1892.
Source Firkin
This is a remix of "flower seamless pattern".I rotated the original image by 90 degrees.This is a seamless pattern of flowers.These horizontal wavy lines are one of Edo patterns which is called "tatewaku or tachiwaku or 立湧" that represents uprising steam or vapor.
Source Yamachem
Small dots with minor circles spread across to form a nice mosaic.
Source John Burks
From a drawing in 'At home', J. Sowerby, J. Crane and T. Frederick, 1881.
Source Firkin
The original enhanced with one of Inkscapes's filters.
Source Firkin
The classic 45-degree diagonal line pattern, done right.
Source Jorick van Hees
One more in the line of patterns inspired by Japanese/Asian styles. Smooth.
Source Kim Ruddock