I do not know what this flower is. But I think of them as “bunny bites”.

When I was little my grandma had one and kept rabbits. An early memory I have is of plucking these flowers and feeding them to her rabbits, who devoured them rapidly and wanted more. Strange what sticks in one’s mind from childhood.
Every time I walk by this bush in my neighbor’s yard when it is in bloom I remember. I wonder if Grandma ever noticed that all of the flowers within reach of a four-year-old were missing.
If you know what they are called please let me know.