I had been anxiously awaiting to get back out but when I got to my site and dug or TRIED to dig my first hole I literally couldn't get my shovel point in the first inch of soil. It was like concrete!!!. I tried a couple of other places but the whole site was like this.
Texas is known for bad caliche, but I doubt that that is your problem since you indicate East Texas. I lived in West Texas for a bit and the caliche was horrible. I had to use a digging bar to make enough space to set a 5 gallon plant in the yard. General aridity is what causes caliche. I think East Texas gets way more rainfall so you are probably getting lots of clay.
You can surface mark the places where you are getting hits with the MD. I use shorty golf tees if the soil is soft enough to permit - yours sound like this won't work. Frequently hard surfaces are only a surface condition. Go down several inches and things may improve. Soil scientists won't take "No!" for an answer. It's their job.
If you are serious about wanting in for a good signal, then there are several approaches. Get an estimate of the object's depth from your MD pinpointer function and/or your handheld pinpointer. Let this guide your aggressiveness.
Brute force - the digging bar to hopefully pierce the hard surface if the object is likely below the hard surface. Don't wreck your goodie by doing this for a shallow signal!!
Bring in enough water to soften the surface. Make a shallow pit to contain the water to concentrate the moisture. Have patience while it soaks in. Kinda like a perc test for a septic tank burial.
Get a bulb auger and a good cordless electric drill to pierce the hard surface. Yes, it is possible to use the auger to drill up goodies and if you are lucky, it won't beat up the specimen. I sharpened the edge of mine (edge on bottom) to take a deeper cut. Mine is ~3.25" in diameter. You can do close-ology and closely miss your target to dig laterally to the target, soil texture/hard surface depth permitting. Electric drills, water and digging bars are heavy. Park close by if possible.
Combine some of these techniques.
When you absolutely, positively need to know what is down there.