I received many answers to my question about the yellow flowers at 
Terrapin:
 
  "I was curious about the multi-stemmed yellow flowering plant that was 
in great numbers at Terrapin Park.  I have seen it frequently lately.  It 
is not cosmos or black eyed susan or zinnia.  Does anyone know the name?"

Tom Beal provided the first of what appears to be the correct response:  
tickseed sunflower.  He wins the prize, whatever that is.

Thanks to all who answered.

Jim Wilson