I have a question....I want to add some ground lights to light up the two trees in my front yard. They are probably 20-25 feet tall. Any recommendations for type of light to add? I have just a grassy front yard, no flower beds around the trees.

Install these:

https://www.kichler.com/kichler/products/landscape-lighting/accent-lights/spot--flood-lights/3000k-300-lumen-60-degree-wide-flood-azt/
Attach to tree with these fittings:

https://www.kichler.com/kichler/products/landscape-lighting/landscape-accessories/led-landscape-accessories/treesurface-mount-bracket-azt/

Use 12/2 lighting cable & waterproof silicone filled wire nuts.
I'd only install two lights for each tree. You may want to buy a cowl to avoid any glare.
Install the lights off the ground & screw into the trunk 4-6' off the ground (where the tree starts branching). Run the light wire up the trunk & staple it to the tree, hide the wire from the most commonly viewed side.
You'll only need a small transformer, 100 watts at most, thought you may want to go larger in case you want to expand your lighting system in the future.