scarlet pimpernel
Anagallis arvensis
Primulaceae

Here's another non-native wildflower. Oy! Please note, the first picture was taken mainly to show this tiny flower up close and is not related to the unidentified prickly plant the bloom is resting on. It is apparently also know as the poor man's weatherglass due to it only opening on sunny days. I'm guessing the scarlet pimpernel comes from Europe. I didn't know it also has a blue or white version. Cool.