It's certainly worth $20.., but it maybe worth more, it's depends on the "Series" of the bill, e.g. "L", "E", "G", "I", etc., which basically tell you where it was printed
You can compare yours to what 1969 $20 bills are going for on Ebay.
Its worth $20..... To be worth anything if not very old they have to be in perfect condition... Anything confederate or large oversized bills is what you want.
Keep @ it and HH !!!
It would be worth keeping it for the future. It will have to go up in value in the near future. When they changed the style to the newer counterfit types of bills, the government destroyed the style like you have as they wore out.