Brandon
To identify the stem one of the most useful items is to know the total length. If you cannot measure it just lay it length wise next to a ruler. Taking good pictures of everything is also key to identify the stem. To narrow down the many possibilities, the stem size and shape are important. The end of the stem, where the handle attaches is called the broach. The little ridges around the broach are called splines. If you can count the ridges, that number can help to narrow down the many different possibilities. If you are not able to count the splines, an in focus picture of the handle end is helpful in determine the spline count.
Glacier Bay is carried by Home Depot and Lowes Hardware.
HJ
Without knowing the total length and only a partial section of the broach in focus, it looks like there are around 40 splines on Brandon’s stem. I guessed Glacier Bay since Glacier Bay has 38 splines (and so does Pegasus and a few others). Some of the Glacier Bay Roman Tub faucets do have brass stems or at least they did in the past