I'm learning guitar thru the
Gibson Learn & Master course, which I recommend to anyone who can't get a good, qualified teacher. In the course, around the 6th session, he gets into strumming patterns.
To show the patterns on a staff, he uses lines that look like notes, but don't have the circles that notes have at the end of the stem, instead they have a slanted line. Those would be quarter notes. Eighth notes have a connecting line between them at the bottom. Half notes have a diamond where the empty circle would be, and whole notes just a diamond with no stem.
Take a look
HERE. Go to page 38, and you'll see what I'm talking about.
I think the strumming patterns are very useful. If you have a number of patterns that you're familiar with, you can try to apply them to a particular song. See if it works, if not, try another. At least you have a starting place. As others have said, you don't have to be married to a particular pattern, but you can use it as a tool to make music.