a tad - fewer than one.
a - one, but not necessarily the only one. Just the one you're talking about.
the - one, and the only one.
pair - two, always, even when it's quite a pair. Could be a brace if you wanted to show off.
couple - usually two, but not as specific as a pair.
few - three to six or so.
several - seven to thirteen (as in "these several states").
about a dozen - eleven to fifteen.
a few dozen- twenty to forty.
bunches - more than forty.
a ton - a whole lot of bunches.
oceans - mega-tons.
bazillion - untold numbers defying imagination.