I keep a few 5 gallon buckets of scraps around to entertain the boss. It makes me much happier seeing her building "castles" instead of sitting in front of a screen.

As mentioned earlier I use stacks and stacks of small bits of timber, I waste absolutely nothing!

All the stuff 1m and under lives in a long rack in the shed, anything 500mm and under lives in a smaller steel rack, and long lengths get stacked in another shed so I can easily see what I have when looking for something. Every so often I'll go through the piles and machine a bunch to a particular size for a specific bulk project, and thickness sand them so they're ready to go when I get around to the project as can be seen by the batch of strips standing up.

I have to say getting a drum sander has been the best investment of all my tools, it has allowed me to make use of timbers I wouldn't have been able to use without it!

I generally only save nicer stuff. Walnut, White Oak, and anything that is not common. like the aged barn-wood.
Maple, poplar, etc go through in such quantity, that they aren't worth saving.
I do save off-cuts of things with special angles, or shapes until the job is done and installed, makes it easier to repair. Once it is gone/done, I throw stuff out.
The main thing I had trouble with was keeping jigs. I would make something for a specific job, knowing that it was probably a "one-off", but keep it anyway. After a while I would forget I even had it, or where it was if I did.
The "cure" for that was clearly writing the details on it with a Sharpie marker.  Job number, date and anything special like router bit diameter and bushing size (if there was one)
I just went through a cleaning a couple of weeks ago, because of an open-house. There was more to throw away than I would have thought.

He's at the age where no matter what project he starts, whether a crane or a robot, he always manages to turn it into a gun or a death ray. 

@teocaf That made me laugh out loud. Made my day, thanks for that.

Dollar stores now offer Sharpie markers in a pack of 6 at unbelievably competitive prices. I'll give them a try after my current stock from Staples (and Amazon?) is used up.

https://toolguyd.com/milwaukee-inkzall-vs-sharpie-markers/

When it comes to shop supplies (pencils, rules, erasers, etc.), I opt for quantity so I can have them all over the place, and have one ready when I need one without having to walk across the shop to get it!

I never mark my lumber or scraps with a felt pen on their ends, a PITA to remove like the barcode tag staples. Sharpie markers (ultrafine) are used mostly to sign a work or label a shop-made jig.

Not me...  Well, maybe.

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ha ha!  You guys make my little bits of scrap look like a non-event!  Once I get a new shop built next year, I'll have about 8 - 10' wall space dedicated for lumber. 

IIRC, that pack of Milwaukee markers had 4 in it, for about $6? Though I do like the idea of retractable.
Adding the initials goes back to the days when I first started in the assembly area. It was more about which machine it was made on, rather than "who" did it. That way, if we ever had a squareness issue, we would know where it came from, since there were 2 large presses. Even a tiny amount can be exaggerated over long runs of upper cabinets, especially with frameless.
I just got into the habit of putting the date with it too.
It's kind of cool to find that on the back or inside of things when they get removed due to damage repair or for an up-date/remodel. In the commercial arena, this happens more frequently than you would think. Wings get remodeled or added to and once in a while there is water damage to a sinkbase and they get replaced. I have seen things taken out in as little as a year, and others well over 10 years, with my scrawl on the back.

Well, if I ever become famous, it will be there.