How do I do anything with a collision event?

Hello,

I have been trying to get it so that the player object can collect a coin (In 2D). I have already successfully used a particle system to create a gun and have it so that when it hits an enemy it sends a messages to call damage. So when I went to try and do a similar thing with 2 GameObjects instead of a particle and a GameObject I figured it'd be pretty much the same, apparently not? anyways this is my problem.

I have the player and a coin, both have Rigidbodies and 2D colliders, and I haven't made either of them Kinematic, mostly because I want them to both still have physics. What I'm asking is how do I use the collision to get information / pass information on. I tried using OnCollisionEnter(Collision collision) and then in there trying to Debug.Log(collision.gameObject.tag) or a million different variations of that but I can't seem to get anything to print to console. Even if it's just a string when any object collides with it.

Sorry if this is a bit of a ramble, I'm trying to describe as much of the situation and what I've done as possible because I don't really know where the error could be. Please help, thanks in advance :)