It's an Oxalis and nothing, short of concreting over your garden, will get rid of it forever. You just have to smother it or pull it. Btw its edible if that's any consolation.

Unfortunately, there is nothing that will get rid of any weed "forever"!! The reason this one - Oxalis corniculata or creeping wood sorrel - keeps reappearing is due to a seed bank that just keeps producing. It can also spread stoloniferously.

But it does respond very well to manual removal. You just need to keep at it to reduce that seed bank in the soil and that is best done before you see any signs of flowering. It takes more than just a single season to effect full control but you will see improvement almost immediately. And mulching will also help to retard the spread and the easy seed germination.

TY, The area is boxed in and I have removed all plants from the area, but as known this just does keep coming back.

Gardengal, you said mulch, but what if I put a layer of Plastic over the whole area and also hand remove anything I see growing under the plastic? I will just skip planting any garden plants until I see it NO MORE (I hope - ^j^ - It doesn't look like anything I would want to eat.

Yes, you can do the plastic thing but needs both a lot of sun and heat to be successful, so maybe not a great time of year to attempt. Also, covering with plastic or solarizing will also kill off all the biological life in the soil and given the two choices, I'd readily resort to pulling the easily removed weeds before damaging the soil health.