Hi Black Cat (sorry, I don't know your name). We've not been asked about Arachis hypogaea before, so I've had a good look.
I read one scientific article about the distribution of Gopher tortoises in Alabama, and the Arachis hypogaea does grow in part of their territory, but I couldn't find any evidence that they actually ate it.
I can't find anything specific to say that there are inherent toxins in the leaves, and in some countries the plants are used as forage for livestock. Most legumes, like peanuts, are high in protein and so for that reason we caution to feed in moderation, because tortoises need a low protein/high fibre diet. On that basis I suppose it would do no harm to plant it in the tortoise enclosure, but there are other factors that might warn against this.
One particular problem seems to be that the plant can harbor a particular soil fungus called aspergillus flavus. This fungus produces highly toxic and carcinogenic chemical substances called aflatoxins, on a variety of plants, including the peanut/groundnut plant. If leaves with this mould or fungus on them are eaten then they are toxic to mammals and have been known to cause death. I can't find any reference to toxicity and reptiles, unfortunately, and I also don't know if the presence of the fungus is apparent to the naked eye. There is certainly great concern for animals that eat nuts (which obviously doesn't apply to tortoises), as you can see from this article https://www.parrotalert.com/article/pea ... -parrots-7
I know it all seems very complicated, but in the absence of definite information we usually advise to err on the side of caution, and I think that is what I would advise in this case. I'm sorr not to be more definite, but in the case of many plants there is just no scientific literature on their suitability as food for tortoises, so we have to make decisions based on studies that relate to mammals. I hope this helps and hasn't just added to the confusion!