answer is fasten
Amass-meaning to gather together.
join, meet
crystals
He will attach a photo to his letter.
necklace?
agate necklace
Its a Nebraska Cornhuskers necklace. He's from Nebraska
In the letter you should mention where you will be spending the summer vacation and what exciting activities you can do together. You can also attach a photo of the vacation destination in the letter.
confer
Necklace
You can purchase a letter necklace from various online retailers such as Amazon, Etsy, or specialized jewelry websites. Many brick-and-mortar jewelry stores also carry letter necklaces in their inventory. Be sure to check the options available to find one that suits your style and budget.
The easiest thing to use to attach two pieces of cloth together is a pin.