My earliest memories are at about 1.5, and they're sporadic & mostly sensory. Sitting on the steps with my dog (the feel of the concrete under my thighs and calves, and the sunshine coming through the green, and the silk red hair and pattern of my dog's breathing, and bugs crawling across me, and...). Returning a hair clip (feeling it press into my hands and fingers, and reaching out and handing it over). The feel of tatami on my feet. Blue tiles falling and being outside in the middle of the night (as what seems like a big party) -7.2 earthquake-, being screamed at (don't know if in English or Japanese) something about getting away from the garden (snake?), the feeling of glass under my tongue (licking a window). A swimsuit with a duck on the front, and trying to hold the seams away from my skin and not having enough arms. The way my legs would dangle from the backpack baby holder, and the feeling of the blue foam and the way my mom's hair smelled.
I know I was 1.5 at the time, because we left Japan right after that, and I have new memories of a different place. They're just as sporadic, & visual/emotional/sensory until after my sister was born. It's interesting to ME, because except for the earthquake... none of the events were pivotal, or important. Just random snapshots of life. I don't get a continuous thread of memory until I was 4 and we were in South Carolina... although the *snapshots* gain in frequency.
I also still dream of that period 1-4, and they're in japanese. The peculiar thing is that I (the character in the dream) can understand what's being said, but I (the adult dreaming) can't understand a durn word. Even though they're both ME, and I'm listening with both sets of "ears".
A researcher at the UW has done a lot of study into memory... but all of her work (to the best of my knowledge) has to do with pivotable memory. Events that the people around us remember or know about or talk about. I also don't know if any of her work is with adhd folks (who tend to be eidetic for sensation) or with true eidetic.