From a drawing in 'Line and form', Walter Crane, 1914.
Source Firkin
There are quite a few grid patterns, but this one is a super tiny grid with some dust for good measure.
Source Dominik Kiss
Detailed but still subtle and quite original. Lovely gray shades.
Source Kim Ruddock
Fabric-ish patterns are close to my heart. French Stucco to the rescue.
Source Christopher Buecheler
Prismatic Groovy Concentric Background
Source GDJ
A simple but elegant classic. Every collection needs one of these.
Source Christopher Burton
One can never have too few rice paper patterns, so here is one more.
Source Atle Mo
After 1 comes 2, same but different. You get the idea.
Source Hendrik Lammers
Light gray pattern with an almost wall tile-like appearance.
Source Markus Tinner
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin
A seamless pattern with a unit cell drawn as a bitmap in Paint.net and vectorized in Vector Magic.
Source Firkin
Remixed from a drawing in 'Maidenhood; or, the Verge of the Stream', Laura Jewry, 1876.
Source Firkin
From a drawing in 'Two Women in the Klondike', Mary Hitchcock, 1899.
Source Firkin
Light square grid pattern, great for a “DIY projects” sort of website, maybe?
Source Rafael Almeida
A grid of squares with green colours. Since the colours are randomly distributed it is automatically seamless.
Source Firkin
Remixed from a drawing in 'The March of Loyalty', Letitia MacClintock, 1884.
Source Firkin
Prismatic Abstract Background Design
Source GDJ
A seamless web texture of "green stone".
Source V. Hartikainen
A seamless pattern based on a rectangular tile that can be retrieved in Inkscape by selecting the rectangle and using shift-alt-i.
Source Firkin
This one is rather fun and playful. The 2X could be used at 1X too!
Source Welsley
Prismatic Groovy Concentric Background 3 No Black
Source GDJ
Prismatic Abstract Background Design No Black
Source GDJ