As Physaria didymocarpa subsp. lyrata is normally characterized by lyrate leaves, I wonder if this ID is correct? It certainly looks like Physaria didymocarpa but whether it is that particular distinct subspecies seems unclear.

Here is the description:
http://www.efloras.org/florata...

This site shows a photo that fits the description of ssp. lyrata:
http://www.fs.fed.us/wildflowe...