Where Besides a Traditional Savings Account Can I Deposit a Significant Sum of Money That Will Accrue a Return and Still be Easily Accessible When Needed?

I will be receiving a bequest from a relative. Ultimately I plan to use it to pay down my mortgage and refinance my house in a few months - currently working on raising my credit score. I do not want to leave this money in my checking or savings account and earn little/no interest. Curious if there is a some place other than a savings account to put the money in? Something that will accrue more of a return, but I could still easily access when the money is needed.