I thought oxalis too. It gets yellow trumpet looking flowers but only seasonally...which is why you don't see any right now.
Personally, I left oxalis in my tort pens. They occasionally ate it but among many other things. It's ok in moderation. Many people pull it but as long as that isn't the main green in your yard, I think it's fine.
Oxalis is pretty hard to get rid of by pulling it out. There are little bulbs on the roots, and when you pull the plant, the bulbs stay in the ground, to sprout when the soil is warm enough.
I am with Heather on this. If it is oxalis, I ignore it. At first I was like "OH! OH!! Bad plant. Must get rid of all of it". Then reality set in, there is just no way to get it all out. It's too fine, mixed in with good plants, and reproduces if you even attempt to remove it (or heck even look at it). I don't know if this is one of those plants we say is bad, but it's not for tortoises. Or if like Heather said, once it's just a small part of a diet, if it blends in and does no damage. I do not feed it to mine on purpose, but it is there in their enclosures.
That being said, because you hardly have anything growing in that spot, you could kill it all off and start fresh. If it's in an enclosure, you could even put something like boards or big pavers down, rather then trying to pull or dig it out.
Many years ago I mistakenly thought it was a type of clover and fed it to my big sulcatas. It was just a handful here and there and it made up far less than 1% of their total diet, but it did no harm that I could discern. Still, I remove it whenever possible now that I know what it is. If you dig down under the roots about as deep a a shovel blade and just chuck the whole shovel full of dirt in the trash or onto a dirt roadway, you will get rid of it eventually. If you are persistent it will stop coming back. Even if you just keep ripping out what is above ground it will eventually die off. It can't live forever without leaves above ground. I have it growing on the ranch outside of my tortoise pens. I don't want it spreading, so I just rip it out when I happen to see it and in most areas it is not coming back. There are a few persistent areas, but I really haven't tried that hard to get rid of it. I would not want a small tortoise eating it.
Thanks everyone! I have a ton of it in my yard I think I'll slowly try and get rid of it. And add like bird seed down to get edible weeds. The enclosure is not in use yet. Want everything to be grown and ready for when I do get a tortoise that can be kept in it.