The earliest ones I can verify as being early are of things relating to the horse my mom owned during my first year of life. The horse was a thoroughbred named Zeppa, who had her own stable and paddock on the property. I only have a few memories of her, mostly that she was a dark chestnut color, incredibly tall, and of course had that distinctive horse smell. (The smell of a well-kept stable, while certainly pungent, doesn't really stink. It's more of an earthy smell.) I also remember riding in the car over to Southern States in Vienna (on 123; there's a bank there now IIRC) to pick up bales of hay.
After a year, my parents decided they couldn't afford to keep both a baby and a horse; much to my surprise they sold the horse. I'm still not sure they made the right choice. But that fact firmly places all my Zeppa-related memories in late 1969 or early- to mid-1970, making them my earliest childhood memories.