What kind of patterns are used to mark a PCB?
It seems you are asking about patterns for indicating what board it is for inventory and the like.

There are many options.  At minimum, I like to add:

A short (one to a few word) name in the top silkscreen layer.  Part numbers may be more definitive, but for most people a name is more useful.  Unless you're dealing with the part number regularly, "Grommulator control board" is going to be more useful than "579103B".

The date of board design in the top silkscreen layer.  Again, a formal revision name is more definitive, but a date is more useful to more people.  This is one of the last things I do before finalizing a board, and is therefore usually the date I send the fab files to the board house.  This may seem frivolous, but it's been useful enough times a few years later that I do this routinely.

The short ECAD tool project name in upper case in the top copper layer.  I try to put this near the bottom right corner, but somewhere around the bottom edge, then the top edge, as possible.  I use Eagle, and make up short arbitrary project names for each board.  This is the name of the directory holding the board, and schematic and other files specific to that board.  The BOM, schematic, board fab files, etc, all include this as part of the file name.  I have a fixed rule that two different boards never have the same project name.  This name is really for me, not for anyone else.

I usually end this name in a digit, which is the rev number for that name only.  For example, I might give the grommulator control my internal project name of "grom1".  The next time boards are sent out that differ in any way, the name will be "grom2", etc.  I always make this upper case, so somewhere around the edge of the board will be "GROM1" in the copper layer.  This is usually 75 mil text height.  Others don't care and will largely not notice, but it can be really useful when you can quickly look at a board and find the project files.  Note that you often design a board before a formal name or part number is assigned to it.

One reason to put it in the copper layer is that it's less obvious.  You have to look to find it, whereas the silkscreen markings jump out at you.

The formal part number, if known at the time of board design.  If you know the part number and are sure it isn't going to change by the time the board is deployed, go ahead and put it on the silkscreen.  If known, I like to include both the part number of the bare board and the assembled board.

Sometimes "Serial" followed by a white rectangle in the top silkscreen layer.  A solid white silkscreen area is easy to write on with something like a sharpie marker.  Put it in the lower right corner, if possible, to facilitate writing there by hand.  At least try to avoid tall components below this area.

For engineering prototypes, it can be very useful to write something to identify individual boards.  If boards are serialized in production, then a sticker printed as part of the production process can be put over the silkscreen rectangle.  Find out what size stickers production uses and make sure to leave enough room.