Similar experience to 'Innocent Toddler Discovery'
My oldest memories of myself are of me masturbating, I was around two, and I remember lying in a crib, humping a stuffed animal. Although I never reached orgasm, I received great pleasure from doing this, and damaged the stuffed animal in the process (the fur started to come off, at which point I had to stop, as it hurt more than it felt good).
I do not remember masturbating again until I was older (four maybe), with a different stuffed animal, and at this point, I was able to reach orgasm (at this time, orgasm was simply an abrupt point where humping no longer felt good).
I still only rarely masturbate with my hand, I greatly prefer my bed or pillow for this purpose.