what small physical gift would you give your past self?

A piece of paper with instructions:

Use your tablet to take photos of your home. All rooms, and how and where you sleep. Make sure to remove the scuffed up plastic lens cover first.
At the next visit at the doctor, ask her to talk with her privately. Tell her about your living conditions, show her the photos as evidence. Don't be scared of her, she's actually a nice person. She'll try to help you.
Your mom will be mad, but most likely it's going to be worth it. Help your dad with the clean-up, I am pretty sure he's going to be the one doing that.
Oh, by the way, if you haven't yet done so, don't give your dad neigbor's WiFi password. He'll absolutely juice it by watching HD movies, and they'll get an "unexplainably" higher bill.
Also, don't get a dog. You won't have enough time for him in the future. Just get the fish.
For middle school, definitely don't listen to your dad about there being no "normal kids", go to the A grade. If your results are good enough, why not?
Lastly, here's a gift. Something you wanted so much you stole it from Tesco.

Provided with the note is something better than just the hand crank flashlight I stole. A hand crank radio + flashlight combo!

That's kinda cute lol, hope your doing far better now

Grays Sports Almanac, 1950-2000 edition

Make like a tree and get outta here!
- Butt head!

A CD-ROM filled with advice, requirements, financial planning (nothing outrageous), a plethora of medical advice in regards to depression and ADHD, and a few books in PDF form. Also, a laundry list of "no no's".

700mb can go a long way in this situation. I've thought about it before.

I'm always amazed how little space it takes to store huge amounts of plain text. Especially when it's compressed. That old saying "a picture is worth a thousand words" is off by a few orders of magnitude.
- I remember when CDROMs were first introduced, and available on computers. The advertising blurb was, "able to fit the ENTIRE Encyclopaedia Britanica on ONE disk!" I'll admit, I was pretty impressed, but this was before I had any idea about how information dense the written word is compared to other media.
  
  People used to like to say a picture is worth a thousand words. You can't have much of a picture in 5kB.
- You could put the full text from the entire English Wikipedia on a few DVDs
It needs to be presented as an Encarta CD-ROM or I would not even look at it.
Oh. I would be interested in that! A post/comment from you with the advice, requirements, medical advice pertaining to depression and adhd and a "laundry list of no-nos". Please do say!
- I have not forgotten about your request. Give me time to collect my thoughts, make sure they're cogent, and generally applicable to those who may read it.

earplugs

Tinnitus… yeah.

A handheld time machine

A sampler of every psychedelic I can get my hands on with a note about what shit I'm going to be diagnosed with.

A note to my 16 y/o self saying, “buy as many shares in Apple as you can.” In 1995, they were under a dollar and I could have bought thousands. Ten years later, they’d be worth enough that I could live off the dividends for the rest of my life.

IIRC Apple doesn’t pay divs.
- They do. Tesla doesn’t.
- Steve Jobs had to die before AAPL paid dividends.

A piece of paper with dates and lottery numbers

Can it be my past self from a few days ago? Because I wouldn't want to give my young self any lottery numbers. That Past-Me would become a lazy ass with no values who never learns anything or knows what life is like. Now-Me would appreciate it much more.

Future you is thinking the same thing and not giving you the numbers unfortunately

A rubber chicken with a pulley in the middle

To visit meathook, yes?

my anxiety meds. my life would've been far different and less miserable if i didn't feel like death over a 5th grade fractions quiz

no-timeline-breaking mode: Buster Brown 100% cotton socks. they lack elastic and the mental relief I get from not having my ankle nerves ping my brain all day with "SLIGHT PRESSURE! HEY! HEY!!! JUST A REMINDER THAT YOU'RE WEARING SOOOOOOOCKS" is emancipating.

timeline breaking mode: detailed instructions on getting rich with crypto, majoring in computer science instead of biochem, and oh by the way you're clinically depressed, gay, and a communist just do your best to fast-track self acceptance GOOD LUCK LOL

A pair of boxing gloves with don't quit written on it.

A cheap fountain pen like a Lamy safari. Maybe some brightly coloured ink too.

Growing up I loved pens and my dad had some vintage Watermans he used all the time which were unquestionably Cool Pens but also really "fancy" so I wasn't allowed to touch them, and we just didn't know that way cheaper and less fiddly fountain pens existed because all of his came from the op shop with ink from borders and not an actual pen store. 8 year old me would've been estatic that not only do easier to use cheaper options exist, they're bright yellow and also you can put any colour in them, not just boring black.

...I feel like everyone answering "Powerball numbers" or "apple stocks" is completely missing the spirit of the question