I went last year and there were great flat smaller rocks. Is this only during a certain time? Looking to go this weekend.

No. You just have to look for Them. They are always around. Sometimes You get those in the water by the edge to at least ankle deep, after a good amount of waves have been rolling. Good Luck and Happy Rock Hounding

Have only been one time so far. I was looking for round rocks, but another person in my group found several nice flat ones, 4-6 inches across.

After a strom there is a lot of good finds

I was just there less than a month ago and able to find plenty of rocks of all shapes and sizes!