Hi and thanks for your question and picture of Creeping Wood Sorrel, Oxalis corniculata. Yes, it is persistent and prolific because it can reproduce from seeds and rootstocks.

For small patches, pull the plants when young and don't let them go to seed. For a larger patch, hoe them out, again, before they seed. It looks like you have killed the grass around the plants, so they should be easy to remove at this time.

If you have a large infestation, you can try a product containing glyphosate, but it will kill other broad leafed plants as well. If you want to get rid of it in lawn, use a product meant for lawn care and read and follow the directions very carefully. As with all pesticides, the label is the law and more is not better.

Good luck,