The first pattern on here using opacity. Try it on a site with a colored background, or even using mixed colors.
Source Nathan Spady
Colour version that is close to the original drawing uploaded to Pixabay by pencilparker.
Source Firkin
A seamless pattern with wide vertical stripes colored in pale yellow.
Source V. Hartikainen
Here's a subtle marble-like background for use on websites.
Source V. Hartikainen
From a drawing in 'Storia del Palazzo Vecchio in Firenze', Aurelio Gotti, 1889.
Source Firkin
A grid of squares with green colours. Since the colours are randomly distributed it is automatically seamless.
Source Firkin
From a tile that can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
Geometric triangles seem to be quite hot these days.
Source Pixeden
From a drawing in 'Worsborough; its historical associations and rural attractions', Joseph Wilkinson, 1879.
Source Firkin
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
To get the tile this is based on select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Derived from a drawing in 'Historiske Afhandlinger', Adolf Jorgensen, 1898.
Source Firkin
Bright gray tones with a hint of some metal surface.
Source Hendrik Lammers
This is the remix of an Openclipart clipart called "Maze" uploaded by "any_ono_mous".Thanks.This is a seamless pattern of a maze.
Source Yamachem
From a drawing in 'Handbook of the excursions proposed to be made by the Lincoln Diocesan Architectural Society, on the 27th and 28th of May, 1857', Edward Trollope, 1857.
Source Firkin
A pale orange background pattern with glossy groove stripes.
Source V. Hartikainen
Prismatic Rounded Squares Grid 4 No Background
Source GDJ
This is a remix of "blue wave-seigaiha".I hope this subtle color version of Seigaiha would be suitable for background .
Source Yamachem
Dark, crisp and subtle. Tiny black lines on top of some noise.
Source Wilmotte Bastien
Found on the ground in french cafe in kunming, Yunnan, china
Source Rejon
From a drawing in 'At home', J. Sowerby, J. Crane and T. Frederick, 1881.
Source Firkin
A beautiful dark wood pattern, superbly tiled.
Source Omar Alvarado
An interesting dark spotted pattern at an angle.
Source Hendrik Lammers
Remixed from a drawing in 'Works. Popular edition', John Ruskin, 1886.
Source Firkin