Hey "tyrlich" I think you are right. I am fairly certain it IS virginia buttonweed. Now I need to try to figure out how to kill it without killing the St Augustine. And thankyou "chazparas" for your hypothesis. however, this is not the fabled money weed. good looking out fritomd

Just checked again- -the seed pods are small though likely immature (was expecting a watermelon but nothing close -leaves are a cross between tomato and watermelon, and have thorns on top AND bottom, quite interesting and painful!

Stellaria media, Common Chickweed. Just pull it, although you have left it rather late since it has already gone to seed. Mow lower to stop it flowering in future.

yes, it totally could be. This house had a well tended garden, but in the last couple years I think the owner had some health issues, and we all know how fast weed can take over. I was curious so I let it go, one of the few I did let go. I can't see the leaves at all, they are under the cover of the hosta, and I don't think they are very attractive. But, that particular yellow colored bloom and flower shape seems to look nice to me with the lupine. I'd like to try and emulate that look with something with nicer foliage. If anyone has any suggestions as to what my bloom with the lupine and resemble that sort of color and light, airy, flower, I'd love to hear them. Thank you linaria_gw!