This is the rarest of Brautigan’s books. Four are currently listed on ABE, ranging from $395 (for an incomplete set) to $1,250.

pleaseplantthisbook.com explains:

Richard Brautigan published Please Plant This Book in the Spring of 1968. It consisted of eight packets of garden seeds, each printed with a poem, all gathered in a small folder.

A version is at pleaseplantthisbook.com. Although the cover of the folder (above) appears to be an actual scan, the packets with verses look like digital facsimiles rather than scans.

The Brautigan Bibliography and Archive has lots of info here, including what appear to be scans of the actual packets (scroll to the bottom of the page). The scans are tiny, and clicking on them won’t make them bigger, but if you right-click on any of them and choose “View Image,” you’ll see a larger version.