I apologize that no one has responded to your question sooner. Different experts
come online at various times. I just came online and saw your question. My name is XXXXX XXXXX I'm a biologist with many years gardening experience.
I looked at your photo, and the plant does look like a mint. There are some characteristics we look for. One is that the leaves grow opposite each other along the stem. Your plant does that. Another is that the leaves get smaller toward the top, and yours also does that. Mint flowers bloom at the top in a little spike, just as this plant does. One of the most important things to look for is stem shape, and I'm unable to see that in the picture. Mint plants have stems that have squared edges, rather than being perfectly round. You can take a look for that trait.
From what I can see, I would say the plant is a mint. However, that doesn't mean it's edible. There are over 3,500 species of mint. None are toxic, but many don't taste very good. Catnip and bee balm are two mints in that category. Some species are native wildflowers. To further complicate things, they can interbreed, creating hybrids. Many of them do not taste good.
What you can do is look for the squared stem. If it has that type, go ahead and taste it. If it only tastes a little minty, it's probably a hybrid without much flavor. If the stems are round, I wouldn't eat it. Here is a website where you can read more about various types of mints:
If you have more questions, let me know in a REPLY.