Yea, mine are mica caps... They pop before the shaggy mane, I just found a few shaggy mane last week here, first of the season!
I still don't at all think the shrooms in question are shaggy mane, the ones in my area look nothing like that!
Always smooth white and egg shaped until the cap starts to open, then they get brown feathers, they're also always of a certain size, the caps usually around 6" tall. They also aren't alone often, usually 2's and 3's or more.
These in question are small , brown, fuzzy and growing singly...
I'm sure whatever they are, they're long gone, we may never know...
Either way, I love the taste of any inky!
*EDIT* just used a better screen to look at the pics, they aren't mica caps like I thought, too fuzzy, STILL don't think they're shaggy mane, almost certainly some inky cap though!