I have been collecting words and sentences for a long time. Here is the back of one of my sketchbooks from art college about 14 years ago, I used to glue them very lightly so I could un-stick them when I needed to.
Now I scan in the book pages, cut out the bits I like and make a note of the page number next to the text.
Sentences about weather make me melt. I'm particularly drawn to:
"the February snow"
(from the sketchbook). Words and sentences take on such a different glow when out of context, just sitting there on their own. I also like:
"There's quite a wind today," she said.
Postscript: Cally has a lovely post about collecting words here.