Square, the rapidly growing mobile payments service, announced today the winners of its first ever Square Wallet Challenge.

The San Francisco-based company awarded $10,000 to 20 businesses with the highest numbers of Square Wallet transactions. It was a contest that these businesses didn't even have to enter.

Among of the 20 winners, 17 are coffee shops from across the nation. Other winners include food trucks and restaurants. While most of the winners are located in major coastal cities like San Francisco and New York, several businesses are located in small towns, such as Winchester, KY.

An example: Caroline Bell, co-owner of Café Grumpy in New York, said that her customers adjusted to the new payment method quickly when the coffee shop started to use the technology in June, 2011. Bell said that she's using the cash reward to build a new website. 

Square dropped its transaction fee in 2011 and now charges businesses for $275 per month or 2.75 percent per swipe. Square says it has processed nearly $10 billion worth of transactions (on an annualized basis) and recently gained wide attention after it partnered with Starbucks in August 2012. The company has raised a total of $341 million, with its most recent round coming in at $200 million.