The symbol or hallmark looks like John Deere? Really don't know the type of ruler that you have, it was probably for something specific, just don't know what?
18” Graphic Technology Continuous Forms Planning Ruler listed on ebay says it is rare. Type in John Deere 18" ruler and scroll down, says only one other known and it's in a museum, now there are three. Item #193562685375 they're asking $183.75 plus shipping.
I remember those rulers from when I was at IBM back in the early 80s. We used them for measuring character columns on the 1403 printer (a huge IBM commercial line printer) printouts (green and white continuous fold paper) to check if our PL/I programs were outputting the correct spacing--no one uses this kind of paper any more for computer printouts. They were common rulers produced in the hundreds of millions. I think the eBayer is really trying one on or is an idiot. It'll probably sell for 25 cents (or less) at a garage sale. I'll give you a buck for it plus shipping for sentimental value. They were kinda cool back in the day.