Aside from DHG there's also Glosso (Glossostigma elatinoides), used for lawns, needs very high light or it grows thinly upwards before melting, unfortunately my Amano book is packed in a box atm, or I could be more sure what one you mean. It's one of the 'trademark' plants he popularized, I believe.
There's also crystalwort (Riccia fluitans) as MDK500 said, which can be tied down for use on wood etc... looks especially nice over a round rock, and on branches, I think. But can be used for lawns, too, though not easy as it's a floating plant by nature.
They're both high light plants, and I sure can't grow 'em (they all eventually making it into my filter intake, bit by bit)... and I think serious aquascapists have found superior alternatives these days, too.