There is a really good article on these rare and valuable gold pieces over at Richard Frajola's web site[Press Here]. Richard gives an excellent history of these coins and other in the general category of Colorado Territorial Gold.
That is Pike's Peak on the front of the coin, although they compressed it to look more like an inverted ice cream cone than a real mountain. It was, and still is, a prominent feature of the landscape around Denver.
As to value, here are some catalog entries for coins that look like our picture:
worn: $8000 US dollars approximate catalog value
average circulated: $10000
well preserved: $16000
fully uncirculated: $50000
worn: $50000 US dollars approximate catalog value
average circulated: $100000
well preserved: $160000
fully uncirculated: $500000
It is unlikely that you have a genuine $20 Pike's Peak gold coin. Counterfeits and novelty tokens made for tourists are common. They may be worth a few dollars at most. If in doubt, take your coin to a jeweler for a gold test.