I have pulled like 20. But thats only because i tt and cycle heavily. If you were going real time, i think you would be lucky to see 1 or 2. Because after months and months of weeds and clovers accumulating in your town, i saw like 1.
None, when I started playing it was already starting to snow and all, so I've never seen a clover in my town.
I would love to use them as decorations in town though, I've seen it used with a grassy path and it looked really good. Does it count as a weed though? Like if I had more than ten planted around town would that interfere with my Perfect Town rating?