Dear Mary: I’m looking for a place to earn the best rate of interest on my contingency fund, which is (drumroll, please) about $18,000 and growing. Recently, I came across a “rewards checking account.” It looks like a checking account that pays about 6 percent, when savings accounts in the same bank are at less than 1 percent annual percentage yield. Is this some kind of scam? —Jason Dear Jason: First, let me congratulate you on your very respectable and growing contingency fund! Everyone needs money they can count on in an emergency. Good job, and keep going! Rewards checking accounts are the latest in creative products from banks and credit unions. Whether they’re scams or not depends on how disciplined and clever the account holders are. While I have not seen a rewards checking account paying the rate you quote in quite a long time, I’ll take your word …