The gloves he likes in his size will wear out fast if he uses them a lot. A spare pair nice if one gets worn out or wet. Not just any gloves will do and preference varies among individuals.
Another idea may be to buy a common two pocket nail apron from a lumber yard or big name hardware store ,around five dollars or less and then put a personal or fun sentiment from you on it with permanent marker(s). Nothing to embarrass him to bad or anything though.

He can use it for a finds pouch ,trash on one side keepers on the other, if he uses a Garrett pinpointer one side tie of pouch can hold the sheath for it. With a customized by you pouch ol dad will have a reminder of you during his hunting time even if he,s soloing it .
A decorated similarly pill bottle with cotton batting or a similar padding can go in pouch for special old finds that need pampering till home.
Some second hand stores have deep display boxes with clear covers that hang on wall with all manner of strange things in them that can be re purposed by tossing the contents or using elsewhere, and yes personally decorated and used for display.I know I,m heavy on the personal aspect but his unique finds may be liked better than common money finds,it carries over into whats special in a gift from family . Its neat your considering an interest of his in your question of a gift. Batteries if he uses them.A box of baby wipes for muddy hunts maybe.