First, you can search and collect one-move checkmate books. There are a few on Amazon, and my daughter and I will publish a new free e-book on the topic in a few weeks. If you are interested, please sign up our mailing list (on the About page) or follow us on Facebook or Twitter.
Second, you can use chess software. My online store has the following titles: "Chess for Beginners: Elementary Checkmates I" and II, which have 40000 and 77000 mate-in-one exercises.
Another software I strongly recommend is "Chess tactics for beginners 2.0", which includes a side course of 900 one-move checkmate problems. It also lets you practice most basic tactics.
Third, use some websites, such as our blog: http://www.onemovecheckmate.blogspot.com