How do you pronounce the clover-like key (⌘)?

It's called the Command key, abbreviated as Cmd.

Common nicknames are "clover" or "butterfly".

The symbol is based on one used on signs in Swedish campgrounds to note a place of interest; Susan Kare of the original Mac team located it in a international symbol dictionary while looking for something to replace the Apple logo, which Steve Jobs felt was being overused. (The whole story is on Folklore.org.)

On the Apple II, the keyboard featured open-Apple (an outline) and closed-Apple (filled in) keys beside the space bar. On early Macs, the same key had both the Command symbol and an Apple logo printed on it, and so some people carried over the terminology and continued to call it the Apple key.

On newer Macs, the Apple logo has been removed, and the key features only the command symbol and the text "command".

This is usually called the "command" key. Others just call it the "apple" key...