Help Me Figure Out What Exactly Is This Coin Is Please

Sorry, but it's almost certainly not an experimaental planchet. As others have stated, it's a perfectly normal quarter which has been plated with another metal - possibly silver, possibly platinum - after it was struck. These were not plated by the Mint, as Giwalsh stated, but plated by third parties - companies such as National Collectors Mint, or Govmint.com (which, despite its name, is not actually associated with the government mint in any way), or the set posted in this thread, which was produced by Merrick Mint.

These plated coins are often found in circulation, because there is next to no value for them - collectors don't want them, coin dealers don't want them, people on ebay don't want them. So in frustration, their owners take them to the bank and deposit them.

But, as Earle42 said, the weight will convince you.

The people on the Home Shopping Networks and other seller of coins on TV plated tend of thousands of sets of State Quarters with gold, silver, and platinum and the sold them for YEARS. Many of these coins then later found their way into circulation after the unfortunates that bought them tried to sell them and found out that their heirloom treasure was actually just worth face value. These coins show up on the various coin forums very frequently. The Secretary of one of out local coin clubs got two solid rolls of the gold plated ones from the bank.

Over the years I have found several of the plated ones in my cash registers. I've also come across the colorized State Quarters in the wild, plus some that have been painted or decaled with random stuff.