I've sat and read this post all the way through putting off work.
OP, really try not to take peoples responses so personally. You do sound a little over-sensitive. Your initial query was fair enough in AIBU - and you will always get people who will fire out their initial reaction- sometimes that will come across as rude but thats the way mumsnet is.... remember they don't know you, they aren't seeing the whole of you.
People in RL aren't rude to our faces and in many cases that’s because they see the person as a whole. So even if there is something people don't like about us, there may be something they do like and so they don't want to cause offence. Here on mumsnet people are only seeing the things you put out there, not the whole picture, and if they don't agree with you they are happy to comment on what impression it gives of you as a whole. Remember they are not saying what you are like- just how this snapshot of you gives the image of you as a whole.
I think this thread became more than just your initial query. It seems you fanned the fires of peoples disapproval with some of your responses by not taking on board some of the suggestions you were being given. Based on the snapshot I have seen of you, and from reading between the lines, it does seem as if you do have issues mixed up with the giving of toys. If your mother was, and is, obsessed with giving toys but also emotionally abused you then this isn't massively surprising - perhaps you subconsciously equate them in some way- but for people that don't have those issues, seeing a child's joy at receiving gifts outweighs all the negatives of the nature of those gifts. Many people are commenting that they agree with your principles, just that perhaps a child’s birthday is not the time to be enforcing them.
You've had some great suggestions for wording of your invite but your responses have not really shown that you have taken any suggestions on board, just that you have becoming increasingly upset at the criticisms you have received. Remember, people do not know you, they are not criticising you as a whole, just saying what they think based on the information they have. Let’s be honest, the people who receive your party invite may not know you either and surely it’s better for someone on here to say that your wording makes you sound over-privileged or weird than for someone who you will know throughout your child’s school career to think the same thing?
My idea would be to re-read all the positive, constructive replies you have received. Think about what people have suggested. Some have suggested you contact everyone at the beginning of the school year, and some have given suggestions for wording (I like Breadwidow’s). But most importantly do not take this personally. Do not take this as a reason to go off mumsnet, it sounds like it is a useful place for you. If you feel the need, change your name and start afresh but remain part of the community. Maybe you can post on the relationships thread and allow people to help you further explore your relationship with your mother and how this relates to the way you are bringing up your daughter. Bringing up kids is hard for us all and we all want to get it right but there are no right answers. You asked what people would think and people told you. People in RL would still judge you just the same, they just wouldn’t say so.
Btw I don’t think it was you people were laughing at you with the playsilks- I snorted out loud when I read that first wanky description from google! Most of us gave our kids scraps of material but had no idea what the term meant, or what open ended play even was.
Reading through through all the posts I had so many different reactions throughout... but mostly 😮 to the woman who spends £20 per present and buys her kids duplicate gifts from them- what I could do with that kind of cash!!!
And just from my experiences, my kids have waaaaay too many toys. But they don’t play with them much. What they want is me to be hands on with them- whether it be to do arts and crafts or play board games with them or for me to cook with them or be in the garden or whatever as long as it is with me. The last birthdays involved them excitedly opening one present at a time (they had to write a thank you card for each one before opening the next). Then all the gifts got put in a big carrier bag to put upstairs. The bags are still full although they took out favourite gifts. Any still in the bag in about a month will be shoved into the regifting cupboard or may be taken to the charity shop. I know it’s a waste but they enjoyed that time opening them so much and there’s no way I would take that away from them. Oh and just to add, my DD age 6 is super imaginative and her teachers say she is doing great, despite how many toys she has. Don't stress it. If you're having lots of input with your kids, then that's the most important thing, not how many toys they have.