From a personal standpoint, A face-to-face thank-you is always the best as long as it isn't during their busy time.AChristmas fruit basket along with an offer to share some of the venison from your harvest(especially some deer sausage) also goes a long way in forming a good bond withlandowners. Look at it this way, if you allowed someone on your property, but you never saw them except for the first time you granted permission, what would you be thinking? I'd think they didn't appreciate it very much.