i am an american myself and must wonder what an american birthday cake is?

maybe a specail recipe only his mom could make? or a shop in usa that baked great and he can not match that taste.
all birthdays in usa are the same as anywhere else. plain cake with white icing and candles on top? or cake with jam? or chocolate? or just a cupcake? or if he loves pumpkin or pecan pie or apple pie so be it. maybe he wants a pie instead of cake?
same birthday cakes in usa are sold in england. i do not know what an american birthday cake is?
just like a wedding cake. there is not typical americain wedding cake. it is the same cake you buy, make or order in england. i lived in england and all weddings and birthdays tasted the same in either country.