I have 2 accidents on car fax does that make my car worth $500?

Only if it was totaled and now has a salvage title. Just look up the value online through Kelly Blue Book. You just plug in the options, mileage, and other criteria and it will tell you the value. As long as the car was professionally restored to original through a body shop, it shouldn't drop your value down to $500. If you just fixed it yourself and slung Bondo all over, then yes, it wouldn't be worth much.

$500.00 is a little bit low. It's worth 2X that at the salvage yard for example.

Depends on the accidents. If you're talking trade in value 500$ is a lot. Dealers don't want to pay at all for trades to begin with, with a bad car fax it makes it even harder. Does the car have frame damage? Has it been repaired? Front impacts or rear? Everything plays a factor.