I’m not a linguistic expert, but fall in my experience is common to all of the US. I would say that autumn is used less frequently (I would say that is debatable) but fully interchangeable. You could maybe even say that autumn is the more formal sounding to an American English speaker. Autumnal isn’t very common. You might read it occasionally but you wouldn’t likely hear it in everyday speech. Other American English speaker’s pleas chime in.

On the lamb front, yes lamb isn’t nearly as common as beef, poultry or pork. The availability of lamb varies from location to location. I would say that most large grocery stores would have some lamb. Maybe not so much in small town USA.

As a side note you can very quickly get a good idea of where someone is from in the US if you ask them how they refer to Coca Cola or Pepsi. In the Midwest (where I’m from) Pop is the most common. In the South it’s a coke (even if it’s Pepsi) or soda. Northeast is mainly soda and the West is a mix. http://www.popvssoda.com/

Eddie

: Right, apologies for the stupid questions, but a couple of thing
: that I've been wondering about recently.

: In the US, as far as I'm aware, the season of Autumn is referred to
: as 'Fall' (or The Fall)..couple of questions... 1) is this
: universal across the US, 2) Do you use 'Autumn' at all. Here
: (UK), we might describe the weather, and or scenery as being
: 'Autumnal'.. do you use this, of is there a 'Fall' version?

: The other query.. I was listing to a UK radio show, and the
: presenter mentioned that not much lamb is consumed in the US,
: and it is difficult to get hold of (for a home cooked Sunday
: lunch or even out at a restaurant). My first thought was that
: this is a load of rubbish, but is there any truth in it?

: Cheers
: Stewart