True silkworms are domesticated moth caterpillars from Eastern Asia and do not occur in the wild in North America. We do have a native moth family sometimes referred to as wild silkmoths, but they are not the same species, and their cocoons generally look different than this. Maryland is home to hundreds of moths species, so we can't identify which one this is from the cocoon alone. If you're curious, you can place them into a container (not airtight) with a few twigs for climbing once the moth emerges, and wait to see what hatches, though it's hard to guess when that will be. Sometimes moths do not emerge but instead a parasitoid wasp comes out instead, if it had killed the caterpillar while it was in the cocoon.

In either case, you don't need to worry about them, but if you would like to remove them, just pull them off the pots and put them into a natural area so they can hatch on their own. Adult moths do not bother plants (their either drink nectar, fruit juices, or don't eat much of anything), but what species of plant(s) their next generation of caterpillars will eat, we can't say without knowing what species it is. Some are very generalist with a broad palette while others are highly particular about what plants they can feed on.

Miri