You could send some Black Eyed Susan seeds. The Amazon link was way to long but search and there are some packets for $5ish.

How about this shirt? https://www.amazon.com/Peace-Baltimore-Oriole-Bird-T-Shirt/dp/B096TB78X1/ref=mp_s_a_1_16?dchild=1&keywords=baltimore+oriole+bird&qid=1629413736&sr=8-16

Depending on how much you are willing to spend:
https://www.amazon.com/Kettle-Classic-Chesapeake-Variety-3-Pack/dp/B07DC9F2F6/ref=mp_s_a_1_6?dchild=1&keywords=utz+crab+chips&qid=1629413956&sprefix=uts+crab&sr=8-6

Great Blue Herons are not specific to Maryland but we do have them on the Save the Bay license plates. Maybe a something with a heron it?