I enjoy it when people say hello and smile at me, even if I don't know them. When I lived in the eastern part of the US, it wasn't done (not at that time, anyhow), but it is regularly done where I live now, and I like saying hello!
If your child is very young, you might see if there is a MOPS (Mothers of Pre-Schoolers) group near you.
Friendship is a funny thing. If what you want most is to have people like you, it's elusive. However, the more genuinely interested you are in *other* people, the more chance you have of making real friends. I am not especially outgoing, so I'm not very comfortable in a large group. However, I can enjoy being with one or two other women, getting to know them well.
Remember that most people have just one or two really close friends. The rest are more like acquaintances - great to have, but a little more distant in relationship.
Talk to other mothers about their favorite subject: themselves! They like talking about themselves even more than they like talking about their children!
You might think about talking to one of your church acquaintances, telling her about your wish to make friends and asking her if she could help you. Like fishing, sometimes you have to put out a lot of lines before you get a nibble. So keep liking yourself, being friendly, saying hello, and asking questions; the responses will come.