Not strictly seamless in that opposite edges are not identical. But they do marry up to make an interesting pattern
Source Firkin
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
This one takes you back to math class. Classic mathematic board underlay.
Source Josh Green
On a large canvas you can see it tiling, but used on smaller areas, it’s beautiful.
Source Paul Phönixweiß
Remixed from an image that was uploaded to Pixabay by Pixeline
Source Firkin
From a drawing in 'Resa i Afrika, genom Angola, Ovampo och Damaraland', P. Moller, 1899.
Source Firkin
If you’re sick of the fancy 3D, grunge and noisy patterns, take a look at this flat 2D brick wall.
Source Listvetra
Bumps, highlight and shadows – all good things.
Source Badhon Ebrahim
Tweed is back in style – you heard it here first. Also, the @2X version here is great!
Source Simon Leo
Formed from a tile that can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
Just to prove my point, here is a slightly modified dark version.
Source Atle Mo
Remixed from a drawing in 'A Girl in Ten Thousand', Elizabeth Meade, 1896.
Source Firkin
Formed by distorting the inside front cover of 'Diversæ insectarum volatilium : icones ad vivum accuratissmè depictæ per celeberrimum pictorem', Jacob Hoefnagel, 1630.
Source Firkin
To get the tile this is based on, select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
Dark, crisp and subtle. Tiny black lines on top of some noise.
Source Wilmotte Bastien
Formed from a tile based on a drawing from 'Viaggi d'un artista nell'America Meridionale', Guido Boggiani, 1895.
Source Firkin
A seamless pattern from a tile drawn in Paint.net and vectorised in Vector Magic
Source Firkin
Sort of like the back of a wooden board. Light, subtle, and stylish, just the way we like it!
Source Nikolalek
A seamless chequerboard pattern formed from a tile that can be had in Inkscape by selecting the rectangle and using shift+alt+i.
Source Firkin
Has nothing to do with toast, but it’s nice and subtle.
Source Pippin Lee