Sulfur is mined.
It comes from either volcanic areas (it is common around hot springs), or accumulations from the action of anaerobic bacteria on sulfur compounds in sedimentary rocks. Sulfur is abundant (one of the primary constituents of smog ;) ) but elemental sulfur less so.
Until 1900 most of it came from Sicily. Nowadays a lot of American sulfur comes from east Texas and Louisiana.
Sulfur inhibits the growth of fungii, which is why it is used as an anti-fungal agent for plants. It also interferes with the browning enzyme which is why fruit is often sulfured before drying, and why the salad in restaurant salad bars often contains sulfiting agents.
Oh, in old books, you see sulfur referred to as "brimstone", as in "hellfire and brimstone".