Illustrated Architecture Dictionary

Corner block
Also called a trim block

A square, relatively flat block of wood, often decoratively carved, placed at the upper corners on each side of the wood framing around a door

Bull's eye design sometimes found in Federal and Greek Revival styles where lintels are plain, a simple central panel and corner blocks being the only embellishment.

Foliate corner blocks are often found in Victorian interiors. 

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Examples from Buffalo architecture:

• Illustration above - Dr. and Mrs. Hubbard A. Foster House Victorian flower
  
  
• Buffalo Athletic Club Bull's eye
  
  
• Dr. and Mrs. Hubbard A. Foster House Leaf design
  
  
• Coit House  Federal bull's eye corner block
  
  
• Hull House Federal bull's eye corner block
  
  
• Photo: Acanthus corner block
  

Other examples:

• Rider-Hoplins House, Sardinia, NY Bull's eye
  
  
• Rose Hill Mansion, Geneva, NY Anthemion