Another pic:

Pumpkin,
looks like fountain grass, dwarf variety.
Mabey a neighbor has it and it seeded into your yard.
It is an ornamental grass.
You know, even if it wasn't, if you like it, keep it.
Just take the seeds off the little bloom when they turn brown and grow them in some soil watering frequently.
Then you can plant them anywhere you want when they get big enough.
Grasses are expensive in the stores.

Looks like a Pennisetum, aka "fountain grass", like P. alopecuroides (link below). I often get seedlings of this in my yard, though the nearest plant is several houses away.

Here is a link that might be useful: Pennisetum alopecuroides

It's Green Fountain Grass (Pennisetum setaceum), an African native now considered an invasive species. It is naturalizing along our roadways and choking out native grass species in rangelands. Livestock doesn't eat it and it creates a hazard for wildfires.

Use Purple Fountain Grass or any of the Muhlenbergia grasses instead. Purple Fountain grass It is sterile but looks the same as the green variety with just a tint of purple in its leaves and seed heads.

Here is a link that might be useful: Invasive species