Questions for the Garden Experts

After a trip to the CACG this morning, I have a few questions for Bob, David, Jenn, or anyone else who may have some answers.  Feel free to reply back in the comments, or shoot me an email!

1) These mushrooms were spotted near the middle compost bin. Anyone know what type of mushroom this is?

2) I found some fresh straw placed on the old potato towers near the greenhouse.  Anyone know what is planted in those?

3) I used a pitchfork on the compost bin on the left for a bit while the kids played in the garden fort - any thoughts on how this bin looks, and any next steps for it?

4) Is the middle bin looking ok?