It had been so long since I'd seen one of these that I'd forgotten its history and had to scour my computer to find my notes on it. While I doubt the original poster will ever see this now, I hope that some of you Disney collectors will enjoy the story.
The only information I have ever seen on this is that it is a replica of an original souvenir plaque given to guests who attended the dedication of the Disneyland monorail in 1959. My wife found a description of this item in a price guide to Coca-Cola collectibles that told an amusing story. It said that the artist who originally designed the plaque for Walt fell on hard times in the late 1960's, and he started to make and sell these replicas. The gist is that these were supposed to be door push plates - possibly for the Coca-Cola Refreshment Corner at the top of Main Street considering the source of this information. Just as Disney's lawyers were about to sue him for copyright infringement, the man died. Subsequent to his death, the artist's estate and the remaining plaques fell into the collector community. There was no indication of how many of these plaques were made originally or illicitly. So its remotely possible that you have an original, but there's no way to tell for sure so it really doesn't matter. There's nothing like a good story to add some spice to a collectible like this. We had a couple of them in the mid-1990's and sold them for about $75.00. That's probably a good estimate of its current value.