It is not  an acorn. Acorns have "caps" that cover an actual "seed" which is shaped somewhat like the pointed end of a fat pencil and completely enclosed in a hard shell. That pointed part is easily separated from the cap and is edible by many birds, squirrels, etc.
 I believe what you have is a seed from a cypress tree, perhaps a Leyland Cypress (Cupressocyparis x leylandii)  as they are fairly common trees, usually planted as windbreaks, in this area.