I keep everything, but I don't really have a good reason to. It's not required by our state, but I think I like doing it because it helps me feel accomplished and "just in case" I ever need to show what we've done.
I keep everything throughout the schoool year, but when the school year is over I go through it all and just keep a few samples to put in their memory folders (these I will give them when they are older and married).
I've kept everything so far, but I don't have any reason to, and I expect I'll probably toss some things in a few years.
I pick and choose. I don't have to do a portfolio in my state, but I like to keep our boohinds covered I keep random worksheets in a file folder in a filing cabinet in chronological order.
I keep everything (ok almost everything) for one year and then I just keep a couple of items so we can look back and see the progress. It makes me feel better. We are not required to keep anything in our state unless your program is on probation (your child would have to fall below the 33rd percentile-overall on standardized test I believe over two years with not showing progress) which is rare.
I live in a highly regulated state, we have to turn in a portfolio every year after having an evaluation. My portfolios consist of: A checklist of subjects (this I get this from donnayoung.org it's called checklist II) A book log (I also print this from donnayoung.org) A list of days showing our 180 days (yep donnayoung) and then I keep samples of work for each subject. Our evaluator said that a few for each subject from the beginning, middle and end of the year... so I keep about 9 samples for each subject. Then for my own use I keep photos and artwork and whatever else I want as a keepsake. I don't turn these into the school, but they go into their portfolios when the school returns them.