I haven't seen this one before...where are you located? the underside picture is kind of blurry, but is it hairy/fuzzy? I take it none of them have flowered, but if so, pictures would help...are these just starting to come up now, in the fall, or are these pictures from earlier in the year?
No its not fuzzy. Have never seen flowers . But was looking on line for weeds in Texas the Houston area and found cudweed. It looks almost the same but not sure . Thanks for helping.
There is an article about cudweed killing cattle via nitrate toxicosis. But that may be more of a ruminant thing. It's in the compositae family which has some winners (dandelions) and losers (wedelia), so I wouldn't feed it, but wouldn't worry about it growing sporadically in your yard for a grazing tortoise.