Resources (info gathered from a professional and very detailed research, however based only on Western contemporary sources, thus focusing a bit more on the eastern regions nearer the coast)
Cereals (wheat, barley, millet etc, respectively also flour, bread): Very high production in all of Bulgaria (basically, most foreign travellers from that time speak of the Balkan lands as extremely fruitful and plentiful of crops and animals), especially in northern Bulgaria, but the best quality wheat was from Varna and Dobrudzha (in our case – Karvuna and Drastar and their villages). The wheat from Macedonia (Melnik, Strumitsa, Prosek) was also famous, especially the one sold at Thessaloniki (for the Byzantines).
Grapes (and wine): Byzantine Thrace (around Philippopolis), the Black Sea coast.
Fruits (apples etc): Thrace
Stock-breeding: All of the land, but especially in the mountainous areas for the sheep. There was a large amount of sheep and cattle found in Boruy (during one crusade), but also should be in Stanimaka and Tsepina and their villages. Pigs should be found especially in the Belgrade region and northern Bulgaria. Tarnovgrad at that time was also famous for its stud farm for battle horses.
Apiculture (honey, mead, wax): All of the land, but especially in northern Bulgaria (around Tarnovo) and the Black Sea coast. The “Cera Zagora” wax (Zagora was a Western name for Bulgaria) was of the highest quality in Europe at that time and was one of the main Bulgarian exports (as well as the wheat).
Fish: Black Sea and Danubian coasts
Salt: Black Sea coast (Karvuna, Ovech, also other Byzantine settlements like Mesembria, Sozopol, Agatopol etc)
Linen and cotton: Especially in Macedonia (Velbazhd and the Strumitsa area)
Silk: Throughout the whole land, but probably centered around Tarnovo (reportedly with very high quality)
Furs: Especially in the areas of Varna (in our case Karvuna), Bdin and Belgrade.
Mining: Large deposits of gold were mined in the Rhodopes region (around Stanimaka), which was one of the main gold-mining areas of the empire (especially around
Perperikon), but gold was mined in large quantities also near Sofia (in our case – Sredets). Silver and iron deposits were found mostly in the mountains like the Balkans (Krun-Boruy), Rhodopes (Stanimaka-Tsepina), Macedonian mountains (Velbazhd) and the ones near Sredets.