If you don't mind doing a little off the beaten path driving, this little stop is fun for those who are into quirky things. The directions I found were perfect. 350th St that brings your directly to the tree IS a poorly/unmaintained seasonal road. We managed it ok in our SUV, but it was lots of mud and off-roading.
Best directions to get to the tree and back to the interstate:
Take exit 70 off I-80
From 80 west, it's a right hand turn onto 750th St (left from 80 east)
Drive about 3/4 of a mile to 740th St and turn left
Drive for about 3 miles and turn left onto Nighthawk
You'll see the tree as you crest the hill (it's at the intersection at the bottom of the hill)
GO BACK THE WAY YOU CAME! Taking a left at the tree onto 350th St will lead you onto the muddy/season road. Unless, of course, you want a little adventure....
What a great park! Worth the 15-20 minutes to walk the whole block. Highly recommended. Easy to get to, on street parking also easily located.