Derived from a corner decoration itself found as a jpg on Pixabay.
Source Firkin
A seamless web background with texture of aged grid paper.
Source V. Hartikainen
A light background pattern with diagonal stripes. Here's a simple light striped background for you.
Source V. Hartikainen
Abstract Ellipses Background Grayscale
Source GDJ
Sharp pixel pattern looking like some sort of fabric.
Source Dmitry
ZeroCC tileable mossy (lichen) stone texture, edited from pixabay. CC0
Source Sojan Janso
Prismatic Polka Dots 3 No Background
Source GDJ
A large pattern with funky shapes and form. An original. Sort of origami-ish.
Source Luuk van Baars
From a drawing in 'Artists and Arabs', Henry Blackburn, 1868
Source Firkin
Remixed from a drawing in 'In an Enchanted Island', William Mallock, 1892.
Source Firkin
A background pattern inspired by designs seen in 'Burghley. The Life of William Cecil', William Charlton, 1857.
Source Firkin
A comeback for you: the popular Escheresque, now in black.
Source Patten
Background formed from the iconic plastic construction bricks that gave me endless hours of fun when I was a lad.
Source Firkin
Remixed from a raster on Pixabay that was uploaded by ArtsyBee.
Source Firkin
Remixed from a drawing in 'Maidenhood; or, the Verge of the Stream', Laura Jewry, 1876.
Source Firkin
ZeroCC tileable stone texture, edited from pixabay. CC0
Source Sojan Janso
The image depicts a seamless pattern of a Japanese family crest called "chidori" in Japanese .A chidori in Japanese means a plover in English.
Source Yamachem
Remixed from a drawing in 'Line and form", Walter Crane, 1914.
Source Firkin
From a drawing in 'Cassell's Library of English Literature', Henry Morley, 1883.
Source Firkin
Don’t look at this one too long if you’re high on something.
Source Luuk van Baars
To get the tile this is formed from select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Psychedelic Geometric Background No Black
Source GDJ
Nicely crafted paper pattern, although a bit on the large side (500x593px).
Source Blaq Annabiosis
A seamless pattern formed from a modified version of rwwgub's tile. To get the tile, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin