As far as fabric patterns goes, this is quite crisp.
Source Heliodor Jalba
More in the paper realm, this time with fibers.
Source Jorge Fuentes
Like the name suggests, this background image consists of a pattern of dark bricks. It may be an option for you, if you are looking for something that looks like a brick wall for use as a background on web pages. It's not a masterpiece, but looks pretty nice when is tiled.
Source V. Hartikainen
Black brick wall pattern. Brick your site up!
Source Alex Parker
Zero CC tileable hard cover green book, scanned and made by me. CC0
Source Sojan Janso
A seamless pattern formed from a square tile. The tile can be retrieved by selecting the rectangle in Inkscape and using shift-alt-i.
Source Firkin
The first pattern on here using opacity. Try it on a site with a colored background, or even using mixed colors.
Source Nathan Spady
Looks a bit like concrete with subtle specks spread around the pattern.
Source Mladjan Antic
Nicely executed tiling for an interesting pattern.
Source Ignasi Àvila Padró
Looks like an old rug or a computer chip.
Source Patutin Sergey
Redrawn based on a drawing in 'По Сѣверо-Западу Россіи' Konstantin Sluchevsky, 1897.
Source Firkin
Here's an yet another seamless note paper texture for use as a background on websites.
Source V. Hartikainen
An orange vertically striped background pattern. Feel free to download and use this orange background pattern, for example, on the web). It resembles a wallpaper with vertical stripes or something similar to it.
Source V. Hartikainen
You know you love wood patterns, so here’s one more.
Source Richard Tabor
To get the tile this is based on, select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
ZeroCC tileable stone texture, edited from pixabay. CC0
Source Sojan Janso
It’s like Shine Dotted’s sister, only rotated 45 degrees.
Source mediumidee
The tile this is based on can be had by selecting the rectangle in Inkscape and using shift+alt+i
Source Firkin
To get the tile this is based on, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Prismatic Polka Dots Mark II No Background
Source GDJ
CC0 and a seamless pattern from a tile drawn in Paint.net .
Source SliverKnight
Seamless , tileable CC-0 texture. Created by my own, feel free to use wherever you want!
Source Linolafett