This one could be the shirt of a golf player. Angled lines in different thicknesses.
Source Olivier Pineda
A seamless pattern formed from a sports car on clker.com. To get the tile, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
The image depicts a seamless pattern of a Japanese family crest called "chidori" in Japanese .A chidori in Japanese means a plover in English.
Source Yamachem
Brushed aluminum, in a bright gray version. Lovely 2X as well.
Source Andre Schouten
It almost looks a bit blurry, but then again, so are fishes.
Source Petr Šulc
A nice looking light gray background pattern with diagonal stripes.
Source V. Hartikainen
Prismatic Polka Dots Mark II 3 No Background
Source GDJ
Prismatic Hexagonalism Pattern No Background
Source GDJ
Vertical lines with a bumpy, yet crisp, feel to it.
Source Raasa
A seamless pattern of dark bricks. Maybe it's not very realistic, but it looks good in my opinion.
Source V. Hartikainen
Medium gray fabric pattern with 45-degree lines going across.
Source Atle Mo
He influenced us all. “Don’t be sad because it’s over. Smile because it happened.”
Source Atle Mo
A simple example on using clones. You can generate a nice base for a pattern fill quickly with it.
Source Lazur URH
To get the tile this is based on, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
As far as fabric patterns goes, this is quite crisp.
Source Heliodor Jalba
Sharp but soft triangles in light shades of gray.
Source Pixeden
A dark one with geometric shapes and dotted lines.
Source Mohawk Studios