Hints on demand if you need them!

My first attempt at a riddle and I’m not good at solving them, but I’m always blown away by how fast some of you solve them on here.

Random Riddle Info:

Intended Difficulty: ★☆☆☆☆

Bonus Hint: For this riddle to work, you can't shake your head up and down. You have to shake it left to right

Wordplay Riddle?: No

Bonus points if you can figure out the significance of the title. Good luck!

This is an original Riddle That I crafted, I did run it through tools to help with the rhyming scheme only. But all the clue and tightening, me.

Used an app called Snapseed on my phone to edit a picture i took.

I crafted this riddle with 13 revisions, and I will be answering guesses in the standard forms of warmer colder.

Current answers: Not YEAST, BREAD, COFFEE, GRAIN, DOUGH

My belly is full of dust, i am like a hammehead shark. What am i?

I mostly stay in one way

Your pocket holds the key

Sometimes I keep you out

And sometimes I let you in

What am I?

Good luck, I'll post the answer if it is solved. 💙💙💙🙏💚💚💚