What colour were the flowers when it was blooming? If yellow, and it grew from a rosette of leaves clustered on the ground, it could be skeleton weed, which is a reportable weed. If so, it would be best to check with the Ag Dept as if it gets hold it can be a big problem.

Not purslane, Portulaca has no markings/nerves on the leaves, leaves are longer, narrower in proportion

The last two are lichens. Try comparing the yellowish one to Candelaria concolor. FataMorgana

After throwing it in a photo program and sharpening up the image, it does look like Carpobrotus to me, too.