Mslexia are looking for previously unpublished female authors to submit their memoirs. Full details are here. This is a competition, with £5000 as first prize.
And, a bit late to the game but still worth mentioning, there’s an ongoing Write Your Own Christie taking place. It’s organised by the official Agatha Christie website. Whilst it’s a competition, I don’t think there’s any money involved in winning but there is a lot of prestige plus a few bits and pieces. Full details are here.