What are some lesser known rap artists you can recommend?

Pretty new to hiphop as a genre, but I have really enjoyed a lot of rap in the recent months. Mainly Mainstream stuff like Kendrick, Kanye, Travis etc.

The most "Underground" I've got was maybe JPEGMAFIA or MF DOOM.

Would love to get a little bit deeper into the genre, so are there any great rappers you can recommend with preferably less than 1 Million monthly listeners?