I don't recall receiving anything in the mail from Google. Or maybe it got lost in the mail. Who knows. I only earned $131 from Adsense last year. Is it so insigificant that Google didn't deem it as worth generating a 1099-MISC form?
Payers don't have to issue a 1099 unless they paid you at least $600. Google didn't have to issue you one since they paid you less than that.
You dont have to declare any earnings if it is below $599 so don't worry about it, sit back and enjoy your earnings.