We are pretty new to bdsm, so keep in mind it may be a while yet before I bring it up with her, but I like the idea of a collar for my sub wife. She has specifically said before she wished she had something to wear when she was thinking about me (I don't think she meant this as it was before we started bdsm). We are not 24/7, nor do I want to be, so I think it would be nice if she had something to wear to nonverbally show that she's in the mood to submit. I feel like a collar could kill 2 birds with one stone here. Something to wear when she's thinking of me and also something that, when being worn, says "do whatever you want, no need to ask".

So my question: how do I tactfully bring this up? Outside of the bedroom, I'm a somewhat shy guy. It's a bit embarrassing to think of talking to her about this. I know she wouldn't make fun of me but I cant get rid of the dread. I just dont want to weird her out or take things too far. I dont want to overwhelm her. Any advice on things to say or small hints to slowly introduce the idea would be appreciated.