This just started popping up in my yard after 7 years here.
this plant is Phyllanthus tenellus, a weed that has been spreading in our area, but was previously only common in Florida. It comes in with potted plants from the south of us, usually. The common name is either ‘long-stalk phyllanthus’ or ‘Mascarene leaf-flower’, and it is in the spurge, euphorbia, family. It is an annual and easily pulled out, but produces many seeds that will hang around, so one must get rid of it sooner rather than later – that is unless you like it!
Steve Hill, Botanist, SCNPS