This is so subtle: We’re talking 1% opacity. Get your squint on!
Source Atle Mo
Actually remixed from a pattern on Pixabay. But then noticed a very similar one on Openclipart.org uploaded by btj51q2.
Source Firkin
Prismatic Polka Dots Mark II No Background
Source GDJ
A pattern drawn in Paint.net and vectorized in Vector Magic.
Source Firkin
Prismatic Hexagonalist Pattern No Background
Source GDJ
Abstract Geometric Monochrome Pattern Prismatic No Background
Source GDJ
Fake or not, it’s quite luxurious.
Source Factorio.us Collective
From a tile that can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
Embossed lines and squares with subtle highlights.
Source Alex Parker
Real snow that tiles, not easy. This is not perfect, but an attempt.
Source Atle Mo
Smooth Polaroid pattern with a light blue tint.
Source Daniel Beaton
An alternative colour scheme to the original seamless pattern.
Source Firkin
Derived from an image that was uploaded to Pixabay by Darkmoon1968
Source Firkin
A seamless pattern of leopard skin. It should look nice as a background element on web pages.
Source V. Hartikainen
White fabric looking texture with some nice random wave features.
Source Hendrik Lammers
Tiny little flowers growing on your screen. Nice, huh?
Source Themes Tube
A free background pattern with abstract green tiles.
Source V. Hartikainen
Remixed from a drawing in 'Works. Popular edition', John Ruskin, 1886.
Source Firkin
You could get a bit dizzy from this one, but it might come in handy.
Source Dertig Media
Submitted in a cream color, but you know how I like it.
Source Devin Holmes
Vertical lines with a bumpy, yet crisp, feel to it.
Source Raasa
A seamless gray background texture suitable for use on websites. To me, it has the look of stone. Feel free to modify it to meet your needs (by making it a bit lighter or darker, for example).
Source V. Hartikainen