I know I didn't! I've hiked right past this trailhead many times and never noticed the sign for the Willow Tree Spring Trail, even though it's only maybe 200 feet from the Coe HQ parking lot. It's on the Coe park map, and there's a perfectly good sign, but I just never saw it. In my defense, it's tucked back a bit and easy to miss. I took a walk down to the end of it today to see if there's really a Willow Tree Spring, and there is! There's also a Sue's Spring, a picnic table, an amazing view, and a lot of blackberries at the very end. (I ate some, but there are plenty left.)
I left a cache near the end of the trail, but not quite all the way to the spring. It's at the spot with the amazing view, placed a few feet uphill from the trail in an area of rocks with bright green lichen and a little oak tree. It's a great place to sit and enjoy the view.
To get here, I recommend you keep your eyes glued to your app or GPS to make sure you don't miss the left turn you need to make about 20 feet from the trailhead sign. It's unmarked, and if you miss it, you'll be trudging up a steep hill unnecessarily. (Guess how I know?) You're looking for a smallish container with local camo.
Coe is open 24/7. A fee or state parks pass is required to park in the lot.
Happy Hunting!