Granny squares are so fantastic to make, I adore them. They're pretty much the only thing I'm willing to crochet.
This sunflowery one is from the book 99 Granny Squares To Crochet, and it's #97, made from acrylic yarn.
That book has some classic granny squares in it... I think it's a hard book to come across, but if you can find it, get it. There are some great recommendations in it! It's one of my favourite pattern books, when it comes to yarn crafts.