Im no expert gardener but id think living on a farm you could find plenty of stuff to use for free.
Not right now
There has to be horse farms around you.
I get old composted horse manure, that were bedded in sawdust.
It has around a 6.5 PH which is very good for most vegetables.
I get it already composted , about $ 10. a yard.
Many places will give raw fresh manure to you for free , they haven't figured it out yet, or just don't want to mess with it.
If you have a place to pile it and equipment to turn it over at least once a week.
Be ready for the garden in about 2 months.
Trouble is the weed seeds go right through the horses, and grow like crazy.
I use ground cover cloth to keep them at bay.
If you fill your garden in the fall, cover with a dark tarp, the seeds will sprout , and die off.
But if you turn the bed, more will sprout.
But if you just cover and plant down through the ground cover, you'll have few weeds to contend with.
I make raised beds 3 foot wide , and as long as there's room for.
That way, the ground cover covers the whole bed, and I plant through it ( cutting x's and placing the cuts back in place.)
Run your drip lines under the ground cloth , as new ground cloth will make water run off at first.
Then it will age a little and water goes right through it.
The manure has to be aged, and composted , but it does make very good garden soil.
It's not like it was around here as a kid, with a dairy farm every couple miles.
More like maybe 6-10 in the whole county now.