You can have a solid color with no image but just your title. It’s sleek and certainly the least labor-intensive way to go. But, come on, you can do better than that. At least come up with some sort of design. You must have a budding artist in your family who can create a graphic for you; email that to us, and we can turn it into your cover.
The obvious choice is to cover your book with a photograph of yourself. Then the question becomes: what age of myself do I want to present? You may like your look best at a certain age, which is a good enough reason to dig up a photo from that time. Who you are right now, even with gray hair and a few facial lines, is another appropriate option. You’re looking back on your life from this moment, so the author and the subject of the book are both accurately represented by a current picture. Another good idea is to put your family home or the home in which you grew up on the cover of your memoir. When you choose an earlier photo of yourself, a house or other object, you can run it in black and white to convey the image of a time gone by.