The block (wiht 3 pieces in the arc instead of 4) was the cover quilt for the book "The New England Quilt Museum Quilts" by Jennifer Gilbert.
Here is the link on Amazon:
http://www.amazon.com/New-England-Qu.../dp/1571200754
My Grandmother made me a doll quilt from this pattern and when I saw the cover of the book I bought it.
The comments with the block says it looks like applique but is really pieced -- it is a Laura Wheeler pattern.