Welcome back, @Trey! It is always wonderful to hear from you- hope you are doing well! 
While crystals aren’t my magical backbone (I’ll leave this one to the crystal masters!), perhaps Labradorite and any of the Samhain recommended crystals could be helpful for you:
Here’s one recipe for a Spirit Bottle:
How to Make a Spirit Bottle
- Glass Bottle
- Herbs associated with spirits
- Acorns or nuts
- Cayenne peppers or powder
- Egg shell or powdered sea shell
- Powdered bone or powdered antler
- Cinnamon
- Corn meal
- Charcoal
- Sea Salt
- Graveyard dirt (note : do not take graveyard dirt without asking)
- 3 bent and rusty nails
- Optional: If for family members, include something with a connection to family members
You will also need:
- Photos or object of ancestor
- A skeleton key
- Something sweet (such as candy)
- A black candle
Instructions
Layer the ingredients into the jar and seal with black candle wax.
You can then use the Spirit Bottle in ritual work and to aid in communicating with ancestors.
Source: Guide to the Magical Path: How to Make a Spirit Bottle
I know @Saulamay mentioned making a Spirit Bottle for Memorial Day- perhaps they have some tips for you? You could also try leaving a bottle of Ghost Water or Heather to purposely attract spirits to your altar, although I would suggest adding something specific to your ancestors in order to avoid potentially drawing all the nearby spirits.
If you’d like some additional inspiration, Francisco shared some great tips about offerings for an Ancestor Altar in his post here that you may find helpful.
Also, I know you likely don’t need it, but just a friendly reminder that if you are attracting spirits then it’s always smart to do some extra protection spells on you and your sacred space 
Wishing you all the best of luck, Trey! May you have a wonderful time working with the spirits of your ancestors 
