Was Esau's Birthright also a physical token?

Probably not. Even in our modern era, there is such a thing as a valid, non-voidable, oral contract, and it is enforceable in a court of law, under certain circumstances. If person "A" promises orally to do something for person "B" or to give something to person "B" in exchange for something else (the technical term being consideration), then the two parties have a legal contract.

This assumes, of course, there is no element of illegality and/or coercion involved in the contract, and that both parties are of sound mind and of a certain age (whatever the age of majority happens to be in the particular jurisdiction). If these things pertain, then the contract is valid and can be enforced legally.

In the biblical narrative to which you allude (viz., Genesis 25:29-34), you'll notice that Jacob, the supplanter or usurper, after famished Esau expressed his willingness to sell his birthright to Jacob in exchange for some stew, said,

"'First swear to me'; so he swore to him , and sold his birthright to Jacob" (v.33).

The narrative concludes with this thought:

"Then Jacob gave Esau bread and lentil stew; and he ate and drank, and rose and went on his way. Thus Esau despised his birthright" (v.34).

There was no need for an exchange of a token, or talisman, or "immunity idol" (for you fans of the television show "Survivor") to seal the deal between Jacob and his brother Esau. While in our modern society there is a preference for a contract to be in the form of a writing, an oral contract can still be recognized as valid, just as it was in the days of Jacob and Esau. Despite there being so much at stake in the birthright-for-beans episode, for Esau to swear to his brother obligated him to hew to the deal he had made.

Today, an observant person might object to the deal the twin brothers struck, saying that there was an element of coercion involved on Jacob's part, since Esau was evidently weary and famished, and his brother took advantage of him in his weakened state. That is where other scripture verses indicate Esau's true state of mind.

We've already read in Genesis 25:34 that "Esau despised his birthright." In other words, he did not value it, being as he was a man of appetites as well as an autonomous soul who would rather depend on his skill as a hunter than depend humbly on God to supply his needs. In Hebrews 12, the writer tells us

"See to it that no one comes short of the grace of God; that no root of bitterness springing up causes trouble, and by it many be defiled; that there be no immoral (< Gk. p**nos, an immoral person) or godless person (< Gk bebeilos, vile, godless, and irreligious) like Esau, who sold his own birthright for a single meal. For you know that even afterwards, when he desired to inherit the blessing, he was rejected, for he found no place for repentance, though he sought for it with tears" (vv.15-17; cf. Genesis 27:36).

Before concluding these remarks, I think it appropriate to point out that in Esau's day, the birthright was more than simply a double-portion of goods and chattel (e.g., slaves) which passed from a father to his firstborn son. According to Dr. Anne K. Davis, in her article "Israel's Inheritance: Birthright of the Firstborn Son",

"The inheritance of the birthright was more than the commonly understood double portion of the father’s possessions. The firstborn also received four additional benefits and responsibilities: a special blessing, the office of high priest to his tribe, a position of leadership and authority, and procreative power—all apparently for the role of leading God’s people. However, the son born to the birthright could lose this special inheritance by failing to develop and exhibit commitment and service to God that are characteristic of priestly service and leadership in battle. When the firstborn sons lost their birthright (Ishmael, Esau, Reuben, and Manasseh), this special inheritance passed on to another son considered worthy of assuming a leadership role and procreative power (Isaac, Jacob, Joseph, and Ephraim)."

As we can see from various scriptures, including Malachi 1:2-3, Romans 9:10-13, Genesis 25:23 and 26:34 (where we learn that Esau, against the wishes of his father--see 28:1--took two Hittite women--"daughters of Canaan"--to be his wives), God knew what he was doing when he told Rebekah even before her twins were born that contrary to custom, the firstborn, Esau, would serve the second-born, Jacob. The reason:

". . . so that God's purpose according to his choice would stand, not because of works but because of him who calls . . . [is why God said to Rebekah] 'THE OLDER WILL SERVE THE YOUNGER.' Just as it is written, 'JACOB I LOVED, BUT ESAU I HATED'" (Romans 9:11b-13; cf. Malachi 1:2-3).