I have seen shades like this listed as a drum shade but I would consider it a modified drum.

Shades of Light is a good source. Ballard Designs and Pottery Barn also have drum shades.

Here is a link that might be useful: Shades of Light

Garden Ridge, Tuesday Morning, Homegoods, and Hobby Lobby have lamp shades. Target also has a few. Drum shades are more common than they were a few years ago so it shouldn't be too difficult to find one. If you're near a Lamps Plus, that could me another source.

Thank you for the suggestions. I can't find a shade in this shape with the same dimensions in a brick and mortar or online. I will just have to keep looking.

Lamps plus has shades that come up under the term "modified drum" I also saw a few lamp shades that had that shape at our local lighting shop. I saw them last week when I was shopping for shades for my bouillotte lamps.

Sparklebread, I believe Lowes has your lampshade. I was there yesterday for an errand and stopped to look at their shades, and saw one like this. If you look online for:

Portfolio 10-in x 15-in Cream Drum Lamp Shade

you can see a photo... the remember the shade being lighter ivory than it appears online. But the shape was definitely like yours with a slight curve inward in the middle.

Peony4- That does indeed look like the lampshade I am looking for. Off to Lowes I go ! Thanks!