Please think back and possibly come up with a photo (in your yard), brand or Etc. This is one I c/n almost remember seeing/servicing/using (since the 60s). The power mechanism is almost challenging me but I have done this manually in small or tight areas.

Kawasaki made this.

Here is a link that might be useful: Turbo-Cutter

weed_cutter - thanks much, that looks like the one. I wonder if that attachment will work with my 11 amp greenworks string trimmer...

Maruyama also made an attachment called a "Landscape Blade". I don't know if either of these are still available or if they would fit your machine. If available they will be pricy.

Here is a link that might be useful: pushing 300 bucks

I use a three-pointed blade on my Stihl FS-310 trimmer. Costs about forty bucks, and is re-sharpenable. You wouldn't want to use it to trim close to a building, because it would cut the building. But for whacking down weeds and grass, it is great. There are a variety of blades and trimmer heads available for the FS-310, and I love mine. It has a shoulder harness that makes it easy to use for prolonged periods of trimming.

ZM
(not associated with any product or vendor mentioned or linked)