2020 S US Mint 10 Coin Proof Set with COA & Bonus Nickel OGP. 2020-S US Mint 10 Coin Set Includes Bonus Nickel. Includes Box & COA OGP Box. American Rare Coin and Collectibles, LLC. Who We Are – Experienced. In 1992 American Rare Coin and Collectibles, a Bloomington, MN coin and precious metals dealer was founded on three guiding principles. Experience, Honesty and Reliability. We have a professional staff with more than 200 years of combined numismatic industry experience. Rare numismatic coins, U. Proof and mint products, 90% silver coins, 40% silver coins, currency, or used diamonds, you can trust us to impart sound and reasoned information and highly competitive pricing.