There are many different awards for your students the first and most common in KS1 is 'Champion Writers' this can be called a variety of things and it's often a good idea to match this to your topic e.g. If you're doing newspapers then the title could be 'Best Columnist' or 'Writing Chief'.
Write 2-5 names on the board - these are to be the champion writers for the day. They could get to write with a special pencil or pen and be the ones to read their writng to the class that day and recieve a sticker for their hard work. By rotating their names it is an easy system to ensure everyone had a chance to share their writing and feel 'special' often.
This is just a simple way of rewarding your children and your school may already have a system in place, it's a good idea to have something that you can use for times when you cover another class and want to offer daily rewards. Below is a more long term option.
You could have a Writer of the Week competition where the winner(s) earn a certificate, have their photos taken and put on a prominent display. You could also consider some of the other rewards we've mentioned above.
It's just a few ways to help you celebrate success in class.