Looks as if it's spray painted on the wall. You can be sure that this pattern will seamlessly fill your backgrounds on web pages.
Source V. Hartikainen
From a design found in 'History of the Virginia Company of London; with letters to and from the first Colony, never before printed', Edward Neill, 1869.
Source Firkin
This metal background pattern resembles a metal plate with rivets. Solid rivets on a metal plate.
Source V. Hartikainen
Number 2 in a series of 5 beautiful patterns. Can be found in colors on the submitter’s website.
Source Janos Koos
These dots are already worn for you, so you don’t have to.
Source Matt McDaniel
Abstract Ellipses Background Grayscale
Source GDJ
A seamless green background texture. The image is distributed under a Creative Commons License (like all of the images here).
Source V. Hartikainen
Background Wall, Art Abstract, white Well & CC0 texture.
Source Ractapopulous
A seamless pattern created from a square tile. To get the tile, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Prismatic Geometric Tessellation Pattern 3 No Background
Source GDJ
Number five from the same submitter, makes my job easy.
Source Dima Shiper
A classic dark tile for a bit of vintage darkness.
Source Listvetra
Light square grid pattern, great for a “DIY projects” sort of website, maybe?
Source Rafael Almeida
A large (588x375px) sand-colored pattern for your ever-growing collection. Shrink at will.
Source Alex Tapein
This tiled background comes in red and consists of tiles that look like gemstones. It is more for blogs or social profiles, I think.
Source V. Hartikainen
One more from Badhon, sharp horizontal lines making an embossed paper feeling.
Source Badhon Ebrahim
Vector version of a png that was uploaded to Pixabay by pencilparker
Source Firkin
The perfect pattern for all your blogs about type, or type-related matters.
Source Atle Mo
The image depicts a seamless pattern of a snow crystal.I referred to a book called ”sekka-zusetsu” or "雪華図説" which means an illustrated explanation about snow crystals.This book was published in 1832 (天保3年) or Edo period.For more about "雪華図説",see here:dl.ndl.go.jp/info:ndljp/pid/2536975
Source Yamachem
Pixel by pixel, sharp and clean. Very light pattern with clear lines.
Source M.Ashok