They should as the plant becomes bigger produce slightly bigger fruit. Mine are larger than peas, at first they were small.
Here's a photo, and you can see the ground cherries in the bowl At left, wood bowl has cherries still in paper lanterns, white bowl has husked cherries. At top is a square container with cherry tomatoes (Sungold). As you can see, i know not that well, they are only slightly smaller. Maybe it's the cultivar? Mine are Aunt Molly.
{{gwi:122156}}

This post was edited by Drew51 on Sun, Aug 17, 14 at 23:38

Don't let the poor name of "ground cherry" fool you! Think of these as tiny yellow cherry tomatoes, with more of a fruity character...

I think size has the most to do with the species (there are quite a few) and variety⦠but don't worry about the size as much as the taste, by far the best (sweetest) ones I've had have been the smaller types. The largest are tomatillos, which don't have much sweetness, but rather a nice acidic taste and used like tomatoes.

As others have said, this is normal. The variety Goldie has slightly larger fruit. In addition, give the plants plenty of space - crowding tends to result in smaller fruits.