Dude that doesn't make sense. A half pound is 8 ounces. So you had 8 ounces when you picked them, and then when you dried them you had 8.7 ounces. So they increased in weight when you dried them? Mushrooms are 90% water so when you dry them you are left with 10% of the wet weight.
In the pic with the freshies with the Vermiculite, there are about 2 ounces dry. Wet weight has always been a little irrelevant to me. Especially with indoor mushrooms, because you don't clean the Vermiculite etc off until after they dry. In fact you try to to handle them at all until they're dry. So wet weight smet weight. LOL Good job man. Very nice pickings.