photo taken Nov 13th
This is a perky seedling showing two cotyledon leaves with a few wide red lobes, and the first true leaves with pinnate (feather-like) leaflets. When seedlings get several sets of leaves, it's easier to identify them because the first true leaves are often miniature versions of the leaves on the mature plant that we most readily recognize.
Here is another version of that same plant in seedling stage. This photo was taken 5 days after the first big seasonal rain and the ground was covered with hundreds of these little jobbies. At first, I wasn't sure what these plants were because I didn't recognize the cotyledon shape. In a few days, the next set of leaves appeared and as they unfurled, they revealed a distinct and familiar pattern to the true leaves. Now I can match the two different kinds of early leaves and determine the identity of the smallest seedlings with only cotyledon leaves.
I am not sure why the new cotyledons are green and the older ones are red. It could be the older ones are experiencing a modest amount of drought stress. With hardly any rain in the last few weeks, the plant may be diverting what water it can suck out of the soil with its young root system to the newest set of leaves, and the older seed leaves are dying off. On the other hand, within its first few weeks, maybe the plant has sucked most of the stored nutrients out of the seed leaves and is getting ready to drop them with the onset of a few sets of true leaves.
Now it is your turn to guess. I will post the answer in a few days.