PGN of easy tactics patterns to ingrain.

Puzzle Rush is the easiest way to practice easy tactics patterns. Play it a few fundred times and you will find easy tactics becoming clear in seconds.

I'll throw in my 2 cents. If there are smart phone app solutions, I'm clueless (I'm PC only.)

For online sites, I think notmtwain's suggestion of Puzzle Rush is pretty good, if the timed aspect doesn't bother you.

An untimed site that you might like is http://www.ideachess.com

Although it doesn't give ratings for the tactics, it has three levels: Easy, Moderate, and Difficult. The Easy tactics may be what you're looking for.

Regarding pgn files for offline tactics practice, the solutions are a bit more problematic. I had a hard time finding freely available pgn files that were easy enough for a complete beginner. Most of the pgn files were for intermediates or stronger. There are a couple of "DB-book" sites that can only be found via the Internet Archive, and one of them requires a "secret" password to unzip most of the pgn files. In theory, you could download several of the easiest pgn files from these sites and then delete the more difficult problems, but that would require some grunt work.

A number of years ago, I bought a software package from Convekta titled "Chess Tactics for Beginners", which probably has the level of tactics you'd like. However, you have to use the program's painfully clunky interface. It runs on my older PC, but I don't know if it runs on newer hardware/operating systems. Also, I'm not a fan of Convekta, for various reasons. Unless they learn how to treat their customers better, I'll never buy anything from them again.

For offline tactics practice, I like to use the freeware program called YATT. The tactics aren't timed, and it doesn't keep track of the problem statistics, but it does use a form of spaced repetition. It comes with a 5,500 problem tactics set (easy to hard), and you can add your own pgn tactics files. (You have to convert the pgn file to YATT format first, but it's easy to do that.) You can merge multiple YATT files and even delete individual problems from a YATT file.

https://sites.google.com/site/fredm/

A while back, I bought Bain's book titled "Chess Tactics for Students". (Difficulty ranges from easy to intermediate, with a small number of hard ones.) From this book, I created a pgn file from scratch, and I converted it to YATT format. Right now, this is my "go to" tactics set.

That's awesome! I'd love to get a copy of the pgn file(s) you created from the Bain book. Would you be willing to share?

For the phone, iChess is an app that has nice easy puzzles. It's also free (though you can pay for more puzzle packs). It also allows you to add your own pgn puzzles. I recently created a program that creates puzzles from my games and then I load them into iChess. Once the program is a little more polished, I plan on sharing it with this community.