Puccinia monoica 'Rust Fungus'
When you first look at it it looks like a pretty yellow flower especially at this time of year when there are very few flowers blooming yet. This plant has a rust fungus in the genus Puccinia, Thanks Patrick for the identification and probable cause. "Crucifers (Brassicaceae) in 11 genera are often infected by rust fungi in the Puccinia monoica complex. Infection causes a `pseudoflower' to form that is important for attracting insect visitors that sexually outcross the fungus. `Pollinator' attraction is accomplished through visual floral mimicry, the presence of a nectar reward and floral fragrances"; Bowmont Natural Area, Mustard Family, Brassicaceae 2008 13 Apr_0093acr