Normally I lay low, but 2 times I have been there so I can relate somewhat.
When DD10 was entering kindergarten I wanted to be a part of all I could (after that year we don't seem to get to be a part of anything.) DD15 had a teacher then let us be involved a good bit and I was the room mom and loved it. So at meet the teacher day I said to this teacer that I would love to be her room mom if she wanted one. She said "thanks but I find the moms who are the room mom types are too involved and pushy so I don't use them." I was a little shocked at the words to be honest but I figures I'd still get to go to things.
Well I was very sick for Open House (wound up needing surgery) so my DH went alone. I had never before and never since missed anything at school but it was a pretty bad and I just couldn't go. Well she had announced that there were Conference sign ups but that was it, DH signed up for that but didn't look at anything further. Next to it was sign ups to be a part of their parties for the year. He missed it. It wasn't till Halloween when one of the moms asked me if I was going. I told her I didn't know about it and discovered what had happened. I figured it wasn't a big deal and e-mailed her. She told me sorry but the spots for the whole year were filled and I wouldn't be able to come to a single thing all year!

I went to the Halloween parade with my older DD and got to see my younger DD but I felt bad I wasn't allowed to be with her so I passed by the office and talked to the principal. She said she was sure I misunderstood to talk to the teacher.
So we had our conference and I asked her again, she again told me no and also told me I was smothering my DD. I told her that she was my middle child and didn't want her to have that middle child feeling that I didn't care. She literally made my eyes well up she was so mean. I left the conference early and DH stayed to finish it. He also took this time to tell her our DD was going to miss a few days of school to go to Disney and what days.
When I was leaving I ran into the principal and talked to her. She basically said it was the teachers classroom she could run it the way she saw fit but she would talk to her to let me come to one thing. So I get n e-mail the next day saying I was going to be allowed to one thing, the Thanksgiving party on the very day DH just told her we'd be out for vacation!
Needless to say for whatever the reason I was blacklisted that year, and it felt awful! I have no photos of parties or anything for DD10's kindergarten year and those are memories you can't get back. So I can relate and it feels lousy!
(They replaced her before DD8 went to kindergarten and she had te most amazing teacher ever. What a relief but oh what I would have done for DD0 to have had her. I was at every single event as were all parents who wanted to be and she was so nice to the kids, can't say the same about DD10's teacher.

)