Veronica

These little violet-like plants show up in our yard every year. I think I introduced them with some transplants from my previous house. The ruler tick marks represent millimeters, so the largest flowers are about a centimeter across. I don't know if these are really violets though. From what I can find, all violets (or all viola species anyway) have 5 petals. These all seem to have only 4 petals.

[Update: I've been informed that these are in fact Veronica (common name: speedwell).]

Photographed yesterday using and Epson Perfection 4490 Photo flatbed document scanner with the lid open.

What it looks like in the lawn. Taken with the Sony Cyber-shot. (The cable wasn't long enough to use the scanner.)