Violets are rather difficult to distinguish among different species as they all look alike save for the colour. Our particular violet is yellow, most probably Viola sempervirens.
Violet in Jedediah Smith National Forest
Violets are easy to identify by their irregular zygomorphic (vertical symmetry) flowers and round leaves (not all species). The flowers are quite small. They bloom in late March and early April.
Here is a picture of western dog violet (Viola adunca).
Viola adunca in Patrick's Point State Park