Couple of ideas: snails or cutworms.

Cut worms will cut them off even with the ground.

Bunnies? I woke up one morning and saw a cute bunny outside. Later on I noticed I was missing a few strawberries from the area the bunny was spotted. I felt like the bad Mr. McGregor from the Peter Rabbit story.

Hmmm....I'm now thinking cut-worms as it's exactly as you described - like cut clean from the soil level.

How do I know if it is indeed cut worms?

You can dig around the where the plants were & find them. They won't be very deep.

I just did that - didn't see any. Of course, that doesn't mean that they are not actually there - somewhere....lurking....waiting to pounce...

I forgot to ask (in my panic...), how do I prevent and/or kill cutworms?

Thanks everyone!

I had cutworms get to my containerized peppers and tomatoes last fall. I put plastic drinking cups with the bottoms cut out around the base of the plants like a collar and no more cutworms! Since I had already planted the plants I had to slit the cup and then place it around the stem. Now, I just plant them inside the cup to start with. Push the plastic into the soil a few inches as the worms come up from the soil at night. I learned about this method right here on GW. HTH, Kay

I have had iguanas eat my garden to the ground before in Boynton Beach Fl. where I live.
Plant em if you got em.
Sam