The excel files linked on this page will show you what the state pays the contractor for the top soil and this is for them to furnish it and install it. It also includes them stripping it from one part of a jobsite and placing it elsewhere on the site.

https://www.txdot.gov/business/letting-bids/average-low-bid-unit-prices.html

As I look at the September 2021 excel file for construction I see the following as an example of top soil at the statewide level:

Item - 1606003 Furnishing and Placing Topsoil (4")
# of projects last 3 months - 46
Quantity total last 3 months - 3,352,808 square yards
Average low bid price last three months - $0.72 per square yard of top soil placed (4" depth)

Item - 1606005 Furnishing and Placing Topsoil
# of projects last 3 months - 9
Quantity total last 3 months - 26,202 cubic yards
Average low bid price last three months - $19.95 per cubic yard of top soil placed (depth varies per plans)

The specification for Topsoil for TxDOT projects is here - ftp://ftp.dot.state.tx.us/pub/txdot-info/cmd/cserve/specs/2014/standard/s160.pdf