A cluster of Oregon grape flower buds is going from tightly closed green to more open rose to almost open yellow. Soon happy pollinators will be visiting the blooms. Meanwhile, you can see the thorny holly-like leaves are changing from burgundy red to green.
https://s3.c.im/media_attachments/files/114/105/365/889/668/556/original/b20cb4cac8806035.jpg