Or put them in a pretty tumbler and use it as a door stop. That's what I do. 

In today's moment of "simple DIYs that are so basic you can't call it a DIY" here's what I do around the studio in leiu of actual doorstops. I'm sharing because it occurred to me that everyone has funny things they do in their work spaces that are "solutions" but not necessarily the YOOSZH solution.

Photos of my insta-stop doorstops:

These are simple river rocks in a light shade, avail damn near everywhere. Purchased from CB2.

Tumblers come in just about every vibe. I actually went with vintage lassi cups from India. Partly because they are heavy-ish. Mostly because they are metallic and PRIIITAAY. 

Rocks go in cups. 

Now use as a doorstop why dontcha'?