Hi T.,
You can go to storytimes at libraries, and to playgrounds and anywhere where children congregate that are your son's age. Look around and ask other parents if their kids are in a playgroup. If so, say you're looking for one for your son. If not, they may be interested too.
I got into my playgroup by being in the special beginnings class at St. Luke's when my first was a baby. We're still meeting, and there is a range of 5 year olds to newborns! Some have moved away or dropped out, and a couple have come into our group. One gal joined our group by approaching me at the library. One gal joined our group because I knew her from church. One gal joined because her sister was in it.
You're welcome to check out our group. We meet every 2 weeks all year and different people are in charge each time. (In charge just means someone decides where it will be <a park, their home...>, and brings snacks.)
Email me- ____@____.com
B. in Meridian