In short, the answer is no, Dollar Tree does not sell grass skirts.
Dollar Tree is a discount store chain that primarily sells inexpensive items such as clothes, toys, home goods, and food. While they do sell a few items that could be classified as “grassy,” they are not typically marketed as such, and they typically do not carry any items specifically labeled as “grass skirts.”
Some people might argue that grass skirts are not typically considered to be an affordable item, and that Dollar Tree might be selling them as a novelty item. However, even if this is the case, Dollar Tree would not be the only store selling these skirts; other stores that specialize in selling inexpensive clothing and accessories, such as H&M and Zara, also sell grass skirts.
Ultimately, if you are looking for a grass skirt, you will likely have to find it elsewhere.