Seamless tile drawn in Paint.net and vectorised in Vector Magic.
Source Firkin
To get the repeating unit, select the rectangle in Inkscape and use shift+alt+i
Source Firkin
CC0 and a seamless pattern from a tile drawn in Paint.net .
Source SliverKnight
Prismatic Polka Dots 3 No Background
Source GDJ
A slightly more textured pattern, medium gray. A bit like a potato sack?
Source Bilal Ketab
Seamless Dark Grunge Texture. Here's a new grunge texture for use as a background.
Source V. Hartikainen
Number 4 in a series of 5 beautiful patterns. Can be found in colors on the submitter’s website.
Source Janos Koos
This pack of filters can help you adding a blocky overlay to objects. May come handy at drawing blocks of stone.
Source Lazur URH
This is the remix of "polka dot seamless pattern".The image depicts polka dot seamless pattern.
Source Yamachem
A pale olive green background with a seamless texture.
Source V. Hartikainen
A heavy dark gray base, some subtle noise and a 45-degree grid makes this look like a pattern with a tactile feel to it.
Source Atle Mo
Black brick wall pattern. Brick your site up!
Source Alex Parker
The image depicts a seamless pattern of Japanese Edo pattern called "kikkou-matsu" or "亀甲松" meaning " tortoiseshell-pinetree".The real pinetree is like this: https://jp.pinterest.com/pin/500744052301065077/
Source Yamachem
A seamless background pattern with impressed gray dots.
Source V. Hartikainen
From a drawing in 'Les Chroniqueurs de l'Histoire de France depuis les origines jusqu'au XVIe siècle', Henriette Witt, 1884.
Source Firkin
A seamless web background with texture of aged grid paper.
Source V. Hartikainen
With a name this awesome, how can I go wrong?
Source Nikolay Boltachev
Recreated from a pattern found in 'Az Osztrák-Magyar Monarchia irásban és képben', 1882. To get the tile this is based on select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
This is a grid, only it’s noisy. You know. Reminds you of those printed grids you draw on.
Source Vectorpile
Everyone loves a diamond, right? Make your site sparkle.
Source AJ Troxell