I received some info from the Iowa DNR:
Thanks for your inquiry. We have bounced your pictures around through a few people here and can give you a little history. Net fishing though no longer legal in Iowa was and is a major part of fishing throughout the United States. Hoop nets which look similar to a children’s butterfly net would be positioned in a river and then checked periodically. The tag identifies the net much the same way as an id tag would on a trap line. A quick online check shows that South Carolina still issues them at $10.00 a piece. I would imagine this piece originally sold for 5-10 cents but we have no records going back that far that would identify the retail price or the original purchaser. Hope this helps in your quest and thank you for sharing the piece of our Iowa history with us.
Regards
Justin D. Alliss
Account Manager
Law Enforcement Bureau
Iowa Department of Natural Resources
515-281-6464