you can put just about anything in a well lit 55g. the grass type plant you are talking about is probably dwarf hairgrass or maybe blyxa japonica.
as far as a list of plants... here are the more popular types
http://www.aquaticplantcentral.com/forumapc/plantfinder/all.php
as far as a list of plants... here are the more popular types
http://www.aquaticplantcentral.com/forumapc/plantfinder/all.php