Feather pillows are my favorite,
but are a little tricky to wash,
but not impossible.
First of all, make sure that there are no slits or tears in the covers. What I have done with some of my older feather pillows that I didn't want to toss out . . . placed them in a pillow case that has no holes or tears and securely sewed the sides, giving the pillows a new cover.
Load two pillows at the same time for balance. Set the washing machine on the delicate cycle, using a small amount of detergent. Make sure to put them through a second rinse cycle.
For drying, I use the low setting, throwing in some tennis balls to help them fluff up and dryer sheets to promote a fresh and clean smell. The pillows will take much longer to dry than a normal load. Take them out and fluff them up by hand periodically . . . this will break up any clumps.
Yes, it is a tedious process, but well worth it! You will love the results :)
Note of warning: Make sure the washing machine is set to the delicate cycle . . . I ended up with a machine full of feathers when I used the regular cycle . . . what a mess!