University or other school transcripts usually are the easiest. University transcript (if you went to a 4 year school) plus a letter from your employer stating you’ve been working for the company for X years while physically in Y location should be sufficient. If you’ve been working for the same employer 5 years or more that’s probably enough — can include a sampling of paystubs as well. High school transcripts are even stronger proof than university since there aren’t all that many international virtual U.S. high schools.
I’d stay away from tax returns, voter registrations, etc. you can be registered to vote and file taxes with a US mailing address not in the U.S. (plenty do.) It’s hard to be physically enrolled to attend a U.S. university or high school virtually. Same with work: your employer saying they’ve seen you regularly for 5 years within the U.S. is pretty hard to question.
Other things you can include are: rental agreements, utility bills, paystubs, etc.
Basically any of the “daily life” things your local DMV will count as proof of residency for a Real ID purposes will help.