Not sure what the 'Control Road' is...all I know is the road from Hemet to Idyllwild was formerly the logging road...logs were brought down the mountain by horse pulled wagons...the saw mills were located in Hemet...or San Jacinto...
I agree with the others...Believe you found a melted beer or coke can..probably in a former camping area...in fact maybe it's mine from my teen years...
There are some hieroglyphic rocks in the Riverside campgrounds near the bowl...and others near the former Fern Valley Plank Steak Restaurant...also numerous grinding rocks...lots of oaks in the vicinity...
The log Fort located in the center of the village at one time was occupied by the Idyllwild Inn and Bowling Alley. This was where Zane Grey resided...as teens we hung there also...obviously after his time...
Not sure of the other famous people who lived there...at least it's not as touristy as Big Bear or Lake Arrowhead...do get a lot of people from downhill Palm Springs...
Kick ass area with a lot of history...
And there is gold in them thar hills...