Did you pay for the half board or was it free?
If it was free then you don't get a hotel breakfast and it's in the parks instead - location is dependent on when your stay is so it will say at the top of the voucher you're given. Guests in Sequoia can pick theirs up from the bar but I don't know if anyone else can (or if other hotels now offer this). It is possible to pay for a hotel breakfast once you're there but this is dependent upon availability and since space is precious at the Cheyenne right now the answer would probably be no.
If you paid for the half board, depending on the state the Chuck Wagon is in right now you might have it in there (it may technically be open but limited on space, not sure how it stands right now) or you'll be sent for breakfast at another hotel. Last time I was there it was the New York and there were clear signs pointing you there.
