Hello Lance -

It's great to hear that you're interested in planting native trees! This is a terrific choice to help conserve water, protect soil from erosion, and create a habitat for birds, pollinators, and small mammals.

Two local sources for saplings are Dutchess and Putnam Counties. In the spring they both offer bare-root plants quite inexpensively; you can usually get a bundle of 10 for around $30. (I have personally shopped at both and have had a great experience!) The links below are for the 2024 sales; the 2025 sales should be posted soon.
Dutchess County Soil & Water Conservation District: https://dutchessswcd.org/seedling-sale/deciduous-trees/
DC Seedling Sale 2024 Order Form: http://dutchessswcd.org/wp-content/uploads/2024-Seedling-Sale-Order-Form.pdf

Putnam County Seedling Sale: https://cceputnamcounty.org/events/2023/02/14/putnam-countys-annual-tree-and-shrub-seedling-sale
2024 Seedling Sale Flyer: https://s3.amazonaws.com/assets.cce.cornell.edu/attachments/65562/Flyer_2024.0207.pdf

The NYS DEC provides a list of trees native to NYS: https://extapps.dec.ny.gov/docs/lands_forests_pdf/factnatives.pdf

If you are unsure about the native area for a specific tree, you can verify by searching for a plant and view the maps in the USDA Plant Database: https://plants.usda.gov/

Good luck with your spring planting!  And perhaps add in a few native shrubs, too!
And please let us know if you have any other questions.

~ JeanetteTB