Hi I have seen a lot of corn / grain or the like yellow cumulations in the fields but no actual plants are there any corn or grain field plants?

There is a wheat plant, but no corn. The harvestable wheats are only found on farms I believe.

I wanted to create a field of them , is there a format to be used in a texture for land or are just stating harvesteable?

Do you want your field to contain harvestable wheat plants that you can get a wheat from, or just a field of static grains for landscaping with? If you only want it to look pretty for landscaping, you don't need the harvestable plant. If there are grain fields in the game, there'll be a static mesh and texture you can use.

No I was looking to make a new kind of terrain with dense crops , but I opened another thread for thatproblem .