Tiny Tuesday.....White Flower

The day started off grey, but after the weekly book group get together, I had quick bite to eat and then spent a couple of hours gardening, hard pruning and weeding..very pleasant in the weak sunshine.  I found this little flower in the raised bed and have no idea what it is....about 15cms/6 ins with fleshy green and yellow lily like leaves, flat on the soil....?? Thanks to dbifulco for hosting today :)

Many thanks also for looking in, and the comments and stars :)