Steve beat me to it with #2 at Oak Tree. The front of that green is tiny and crowned, and it's probably 4 feet down to the bottom-back tier.
A couple that have been mentioned already, to me, don't really count as reverse tiers, at least in their present form.
#14 at Prairie Dunes is more like a swale that runs through the back of the green - there is a higher tier at the back. I suppose it counts as a 3-tier green with the low one in the middle.
#2 at Oklahoma City maybe used to be, but now there's just a big downslope at the front of the green. There's no front tier on which to place a hole location. That course is still notable for the number of reverse-slope greens, which kind of fits this category: if I remember right, 1, 2, 4, 5, and 13, maybe more.