sounds like a Miscanthus type... Maiden grass or Gracilimus is the most common

most get bigger than 3 feet when well planted, but there are dwarf forms

See if this is the one you are speaking of
.www.hostas.com/grasses/gallery/grass-26.html
It could be a Miscanthus, but from the height I would suspect a Pennisetum. There are many types of both, so you will have to do some looking.

yeah you are probably right, a "Fountain Grass" Pennisetum... they do look like big mops, they get fuzzy round plumes

Noki and PollyNY, thank you for your suggestions. It is not fountain grass... or gracillimus. The plumes are much different than fountain grass.

Can you post a picture?

Try Molinia - Moor grass. There are several of the Molinia that are in the 3' "mop-top" appearance.

This grass family is not really spoken of on this forum but it is a grass that even I need to get more of in my plantings.

As a side note there is a Molinia "Karl Foerster" that is mounding and the flowers stick up, like fireworks shooting up and away, that is totally awesome compared to the Calamagrostis "Karl Foerster" one of the sentinel at the gate grasses.

Jake