Armillaria spore prints should be white, so make sure to do it on a white paper and black paper or anything light/dark to get better contrast. Galerina has rusty-brown spore prints and Pholiota have grey-brown spore prints.
The yellowish parts on the stem make me think Pholiota.
The flavor "painful-bitter" was it like spicy-hot-bitter? Armillaria luteobubalina is purported to be like that, but us edible. I don't think it made its way to Maryland though. lol Most of the species tastes bitter, but that cooks out. You just need to nail down what it is before even consider trying to eat it.
Since it doesn't look like it has changed color after being sliced, that is also a plus for one of the Armillaria spp. The ring on some of the stems throws me off though. I'd just try to identify them then toss them out later.