Q.Sunflower heads are not flowering
I am trying to find out why my sunflower heads are not flowering. Out of a dozen plants that came up, only one has actually flowered. Is there somewhere I can find pictures of what various pests do to sunflowers? I have tried to upload two pictures of the heads. Any hints would be greatly appreciated. Thank you in advance.

This is most likely due to the Sunflower Midge insect.
I would recommend you contact your County Extension Office to inquire on the best treatment in your region.
Here are some links for you with more information.
http://www.uvm.edu/extension/cropsoil/wp-
content/uploads/SunflowerInsects.pdf
https://www.gardeningknowhow.com/plant-problems/pests/insects/blossom-midge-in-plants.htm
https://www.gardeningknowhow.com/extension-search/