What should I crochet my bf?

I’m still a bit of beginner i’ve learned most of the basics; single crochet, double, half double, triple (i thinks that whats its called) and I also learned the trick with the double crochet to make it so theres no holes, i’m not sure what the stitch is called. I want to make something out of one color bc i have a lot of navy yarn I want to use up. What are some cool ideas I can use with Navy yarn? just one color though im not too good at changing colors just yet. Any ideas? I really want to make him something he could use everyday or at least often.