I keep almost all of my old art. I did at one point throw out some stuff but now I sort of regret it.
My parents have something I made when I in Preschool (so I was 4 or 5). The oldest thing I own on hand is a picture from Kindergarden where I attempted to draw the play-set in my backyard from memory but then messed up the whole pic by accidentally coloring the wall around the yard sky blue.
I started to draw a lot more in 4th grade, so here is some stuff from my late elementary years
Age 10. Rose the Cat. Personality: female.
Also age 10. Weird Sonic inspired character.
Age 11. Original character, do not steal
Age 12. OK, this character with the purple face sort of inspired these characters
I was sort of fascinated from an early age by the concept of birthmarks and skin mutations (another reason why almost all of my comics has an albino person).