What is your earliest memory?

It was well before I turned one; I was still in a crib. It was dark, nighttime, and incredibly hot. Some sort of animal with glowing eyes stared at me from the floor.
I thought it was a dream, but decades later my parents confirmed that when I was a baby the thermostat had broken and we had a night where the temperature was 100°. As for the animal with glowing eyes, that was our cat.

Weird person giving me something incredibly sweet. (Later found out that was a polio vaccination via sugar cube). The memory was very partially formed, but it should have been around 18 months old.
Other fully formed memory starts around 2 and half.

Climbing onto the counter (at 2 or 3 years old) to get a Flintstone's vitamin, because I liked the way they taste. Plot twist: what I actually ate was one of our dog's epilepsy pills.

Nice try to trawl for answers to security questions! I'll never reveal that my earliest memory is playing with my first dog Chestnut in my childhood home on Oak St with my mother whose last name prior to marriage was Jessop!

Playing in the yard outside our apartment: little 3 y.o. me was throwing rocks at a giant wasp hive. Coincidentally, my first memory is also the first time I almost got myself killed. Getting stung is how we found out I'm seriously allergic and now I carry an epipen.

Being in a stroller and the sun being incredibly bright overhead. Must have been around 2 years old.

Prob 3, and making a big ass semi truck out of Lego duplo blocks from my own mind. Thing would fall over because of weight. It had a driver and passenger.

I distinctively remember portions of my little school when I was between 2 and 3 years old, and of playing with my still-to-this-day best friend :P
Further back than that, I can't really remember anything, I don't think.

3 years old, my family was being sealed in a Mormon Temple Ceremony. Kind of a renewal of vows for my parents, but with cult stuff, and us kids.

In a cot looking up to see my family looking down.
- I can't be sure it's not a false memory, but I seem to remember sitting all buckled into one of those removable car seats on the floor of the hallway in our first house. The low perspective is very vivid and the place in the hallway is very specific (the threshold of the living room). That house would put me at under 4, but the angle etc would suggest I was much younger and in an infant car seat. I can never be sure if the level of detail supports it being a real memory or a false one. My first memory's definitely in that house though. I remember in the heat of summer hanging out with my mom in the one room that had an air conditioning unit. But I was definitely ambulatory at that point.
  
  That's pretty much how my memory goes too.

Sitting in the upper part of the shopping buggy being pushed around Wal-Mart. Must have been 2 or 3.

I was somewhere around a year or two old. I can vividly remember me and the two neighbor girls who were 2 and 4 years older than me going into the bathroom and flushing some bath toy down the toilet, my dad being mad, then me asking if I could have it back when he unclogged the toilet.
I also distinctly remember trying to find a toy that for a while I thought was a fake memory that I made up. The toy was a small version of a T-16 Skyhopper that came with a Luke action figure. I had to have been 3 because that toy was 1999 and my memory was when we moved, and I remember that pretty well.
I also remember stepping on a carpet tack in our house, and I can even almost perfectly draw out that house's layout even though it was in my first 3-4 years of life.

Crawling over the wall my crib, and letting myself down, placing my feet between the vertical slats. I was two years old. I remember being two when we moved into our new home, after that, and I had a regular bed there. The new neighbor, when we moved in, asked me how old I was. And said “I’m two.”

Being at MarineWorld (now Six Flags Discovery Kingdom) to see the orca, and the poor creature was just laying in the water motionlessly. my family was there and they were like "aw, it must be sick :("
I think this might be the article for it: https://www.sfgate.com/bayarea/article/Marine-World-Mourns-Loss-Of-Killer-Whale-3303153.php
I probably have slightly earlier memories but I don't actually know which ones are older so I stick with this one

Some scary dark night, some Neon Signs, a low light street lamp, the car doors frooze, so cant open them, so had to climb through the car from the other side.

My mom and dad getting into an argument about how toasted the bread should get in the toaster. I was somewhere between one and three years old.

Couldn't tell you how old, but either sitting on a fold out couch bed in a basement playing that n64 yoshi game or in a nearby room playing some dumd edutainment pirate game.