There are many different types of burgers you can try out there – most of them will need a visit to the supermarket for some extra ingreedients – but it will be worth it!
Here is one from vegweb.com, you will have to source out some textured soy protein granules, but it'd be worth it.
and here is one from savvyvegetarian.com which is also vegan
On youtube 'foodwishes' are promising the best garden burger ever – I've not tried it myself, but with step by step video instructions it should be pretty easy to try yourself:
Mushroom Veggie Burger Recipe – Best Garden Burger Ever!