What can you use to contain a garden?

Hello guys n gals... I planted another garden yesterday, forgot to take a pick to show you all tho.  Oh well... next time.  Thanx again to Celia and the kiddos for waterin the garden last night. 

So I've heard of a few things to use as raised garden square borders... use the comment thingy here and lets see what else we can come up with.  So far I've heard...

Lumber

bricks

tires

bale of straw

and by the way... get well quickly Alan! And hang in there Karen

Happy Gardening, Beth