Gertie,
This heart is made at the same height and in the same fasion as your diamond on another tree.
I see nothing to indicate a sign on the third tree please enlighten me as to what it may be.
The first two were hurridly done and have completely healed over,
judging by the bark and the leaves available you are dealing with Ash trees.
Ash is fast growing and will heal itself qiute quickly, but the scar left will show for many many years .
These marks if large enough could have been left 80 to 100 years ago or more.
If there was anything inside the heart it has long been grown over and is a memory of the past.
I would need more signs to be able to say which of these signs is a first ina series ...
At this point logic tells me the heart came first and the diamond last in the series,
But I have no idea how close together thes are either.
The heart indicates either a declaration of love or a treasure.
The diamond (depending on how it was carved) would indicate a league or a portion of. ... 2.2 - 2.5 miles
Best I can do for now.
Hope you find more
, that would help. But for now you have a cool mystery.