How do you verify "mommy grades"? Do you even worry about verifying grades? I had my kids take the ACT, but have heard of numerous others that do ACT, SAT, SAT II's, CLEP, AP, TABE or GED....of coarse these are all for high schoolers. When my kids were younger, I had them do the Spectrum Test Prep workbooks just to make sure that they were on track. We never did any formal testing back then.
I don't worry about it. I only have my kids take the tests that they need to take. I'd do the ACT or SAT if they wanted to go to college. I'd do CLEP if they excelled in a a subject and wanted to get fast college credit for it. I don't formally test my younger ones; mastery is the only option when you mother is sitting right next to you saying..."No, that's not right...do it again."
Since my grades are for Other People's Kids, I do make a report card and show grades, but I also keep the quizzes, tests, reports, whatever those grades are based on. (I did the same thing when we were hs'ing DS.) I don't keep the work forever, and I don't send papers home to be signed, but if the parent wants to know how I arrived at that grade (I don't use letter grades, only percentage scores) they're able to come look at their child's folder any time. I also do annual achievement tests, and share that with the parents. It's not required by the state or anything, but it's good for me for accountability to the parents. I haven't had any take any of those high school tests, except DS who chose to take his GED, then he took something else to get into his vo-tech school.
