Your picture is of an alien weed with the common name Asiatic dayflower (Commelina communis), so called because the individual flowers last only a day. It can become a fairly aggressive weed, as it grows quickly, and can root at any of the stem nodes that touch the earth. For that reason, you can find it quickly criss-crossing a garden. However, the shallow roots are easy to pull up.
If it looks slightly familiar, it’s because it’s in the same family as the common garden flower spiderwort (Tradescantia occidentalis). Both have a fleshy stem with nodes, somewhat grassy foliage, and petals with a bit of iridescence.