I've run into a lot of my fellow SAHMs by taking my kids to the park. The trick is in figuring out what time they are going to be there.
I kept missing the other moms for a long time at the park. There were just never there when I was. But I always tended to go at lunchtime or later in the afternoon.
I finally started going to the park with my youngest after dropping my oldest off at kindergarten. Voila! There they were, also having their younger children play after dropping older children off at the school next door.
Try Activities
Yes, this costs money. But I've gotten to talk to a lot of other stay at home moms when I've been able to sign my kids up for activities. This especially works when the kids are younger and you have to stick around for the class. As a rule you'll see other stay at home parents, the occasional part time employed parent, and grandparents having fun with their grandchildren.
Try Online
You won't meet so many local moms as a rule, but there are plenty of forums and websites dedicated to stay at home moms. The Internet is full of resources and great people for you to meet. You can be very open about who you are or keep relatively anonymous.
There are also websites that can help you to get matched up with local moms. Just search on "mom groups" and you will find some great resources to help.
Take a Walk
Take a walk at various times of the day in your neighborhood. It can be hard to find other moms out for a walk with their kids sometimes, but it can be done. If you find a fellow stay at home mom, try walking together regularly. It can be a chance to get to know each other even before trying out a play date.
The great part is that many of these are free to do. Others may cost a small amount, but can be worth the expense if they're fun for you and your child. As you get comfortable making the effort, you'll realize how many potential friends you and your child have out there. And you won't feel so isolated.
